Mario Victor Famorca Leonen was born on December 29, 1962, to lawyer Mauro Leonen (d. 1970) and Adrelina Famorca. His parents got married in Vigan, Ilocos Sur but eventually settled their family home in Baguio City, Benguet, where he was born.^[3] He is second-born to six children of their parents. He is of Ilocano ethnicity.

His mother is a pharmacist and a devoted housewife. His father was a human rights lawyer for indigenous Ibaloi people in land title disputes. Before heading to his trip to Manila in 1970, he woke up the seven-year-old Marvic and told him, "Be good. Be strong. Help others." Unfortunately, Mauro met a car accident that caused his death in San Manuel, Tarlac on 26 June 1970.^[4]

Leonen planned to pursue the legal profession since the second grade at St. Theresa's College Baguio.^[5]

After finishing at St. Theresa's College for elementary and at Saint Louis University-Boys' High School as valedictorian, Leonen graduated magna cum laude with a degree in economics from the University of the Philippines Diliman in 1983 and served as chairperson of the organization Economics Toward Consciousness, a student organization based in the University of the Philippines School of Economics, in A.Y. 1982–1983. He obtained his law degree from the university's College of Law in 1987. Leonen was in the top four of his class when he finished.^[6]

From his senior year, Leonen joined the Free Legal Assistance Group or FLAG and won his first case defending rebels captured without a search warrant.^[7] Later that year, he co-founded the Legal Rights and Natural Resources Center, Inc.-Kasama sa Kalikasan, a legal and policy research and advocacy institution that provides legal services to upland rural poor and indigenous people's communities.^[8] He served as the center's executive director for 15 years.^[8] He then left for Columbia University for his Master of Laws degree.

Leonen joined the law faculty in 1989 as professorial lecturer in Philippine Indigenous Law. He became assistant professor during the term of Dean Pacifico Agabin and started to do work as an academic administrator under the term of Dean Merlin M. Magallona. In 2000, he joined the University of the Philippines System administration as university general counsel. In March 2005, he became the first vice president for legal affairs of the UP System. Leonen has taught 20 different subjects in the law school. These subjects are:^[9]

Civil Procedure, Evidence, Criminal Procedure, Special Proceedings, Remedial Law Practicum, Legal Research and Writing, Legal Profession, Constitutional Law I, Constitutional Law II, Contemporary Problems in Constitutional Law, Law and Society, Legal Method, Contemporary Commercial Law Problems: Law and Economics, Contemporary Commercial Law Problems: International Economic Law, Contemporary Commercial Law Problems: Regulation of FDI, Intellectual Property Law, Agrarian Reform Law, Philippine Indigenous Law, Natural Resource Law, and Public International Law.

He also served as director of the clinical legal education program of the college. His teaching competence is not only acknowledged in the CL but also in other institutions, such as Miriam College and the Philippine Judicial Academy. He has extensively lectured and acted as resource speaker in national and international fora such as those conducted in Hong Kong, Thailand, Malaysia, Indonesia, Japan, Spain, Netherlands, Australia, Estonia, and the United Kingdom.^[10]

In 2008, he was selected as the Dean of the University of the Philippines College of Law at UP Diliman by the Board of Regents of the UP System.^[11] He served as Dean until the appointment of Danilo L. Concepcion in June 2011.

Leonen has also provided legal commentary for television networks such as ABS-CBN and GMA Network during the coverage of such events as the 2000-2001 impeachment trial of President Joseph Estrada.

In July 2010, Leonen was named by President Benigno Aquino III as the Philippine government's chief negotiator with the Moro Islamic Liberation Front.^[12] Under his leadership, the government successfully sealed a framework agreement with the MILF for the establishment of the Bangsamoro political entity to replace the Autonomous Region for Muslim Mindanao. His performance was hailed by different sectors in society, bringing new hopes for lasting peace in war-torn Mindanao.

On 21 November 2012, President Benigno Aquino III named Leonen as the 172nd Associate Justice of the Supreme Court of the Philippines at the age of 49. Leonen is the youngest justice named to the Court since 1938.^[13]

In oral arguments, Leonen frequently challenges the arguer's position with his stringent lines of questioning. He frequently uses the Socratic method in order to test positions and arguments of counsel appearing in Court.^[14]

In the landmark case Belgica v. Executive Secretary, where the Court declared the Priority Development Assistance Fund unconstitutional, Leonen wrote a separate concurring opinion where he displayed great command of logic and the law in order to arrive with conclusions regarding the unconstitutionality of pork barrel.^[15] He said, "A member of the House of Representatives or a Senator is not an automated teller machine from which the public can withdraw funds for sundry private purposes."^[16]

In Civil Law, Leonen has also penned many notable landmark decisions including Tan-Andal v. Andal which removed any medical requirement such as paying for doctors as expert witnesses for the declaration of the nullity of the marriage due to psychological incapacity in the Family Code. The new rule only requires totally antagonistic personality structures resulting in the inevitable breakdown of the marriage. The incapacity to fulfill essential marital obligations need only be manifest specifically toward that spouse and not manifested to others, as this would be sufficient in order to declare the marriage as void ab initio.^[17]

Dissents edit

Leonen is known for his frequent dissents in the Court. In an interview with Rappler, he said that while his point of view might often be "before its time,"^{[19]: @47:50} it does not frustrate him to dissent, as in the future, the reasoning in his dissent might be relied upon by the majority,^{[19]: @49:00} pointing to the case of Holmes' dissent in Abrams v. United States as an example where this had happened.^{[19]: @34:00}

Among Leonen's notable work is his powerful dissent in Disini v. Secretary of Justice,^[20] where he argued that the entire concept of criminal libel, and cyberlibel, is an unconstitutional vestige of American and Spanish colonialism.^[21] He's also noted for his dissent in Republic v. Sereno, calling the majority's decision a "legal abomination."^[18] In Lagman vs. Pimentel III, a case which tackled the legality of the extension of martial law and suspending the privilege of the writ of habeas corpus in the whole of Mindanao, Leonen penned a lengthy dissent, explaining that the Congress had gravely abused its discretion as there was no proper presentation of the facts in their proper context, no examination of the allegations of facts by the military, and no ascertainment as to why a longer extension of the same area was needed despite the continued declaration of military victory.

As Bar Chairperson of the 2020-2021 Bar Examination edit

In the Philippines, it is the Supreme Court that exclusively administers the Bar Examinations and every year, a Supreme Court Justice becomes the Bar Chairperson. Leonen was supposed to be the chairperson exclusively for the 2020 Bar Exams (which was postponed), but the scope of his watch got extended to the 2021 batch because of the challenges brought by the COVID-19 pandemic.^[22]

While the final exam date was yet to be settled, the Supreme Court kept the examinees abreast by posting at the Bar Bulletins, a series of Bar-related instructions; while Leonen regularly posted updates and motivations on his personal Twitter using the hashtag "#BestBarEver2020_21".

The exam was first expected to take place in November 2021, but then it got moved to the four Sundays of Jan. 16, 23, 30 and Feb. 6 of 2022. However, because of the Court's dutiful reliance to scientific recommendations and strict compliance to the COVID-19 related orders, it was decided that it must take place on February 4 and 6 of 2022.^[23] The exam was held in 31 localized testing sites all over the Philippines, with each site adhering stringently to the local pandemic protocols and cooperating with the local law and public safety enforcers.

This batch produced 8,241 duly-licensed lawyers out of 11,402 who took it, where 761 were said to be "exemplary passers" with grades ranging from 85 to 90% and 14 were considered "excellent passers" with grades higher than 90%. In this exam, Leonen removed the word "fail" and simply used "did not pass" or "did not finish" to those who did not obtain the grade of 75% or higher.^[24]

The New Lawyer's Oath edit

The Supreme Court En Banc first approved the Code of Professional Responsibility and Accountability (CPRA) on April 11, 2023, after a nationwide Caravan that was participated by several members of the legal community as well as the lay people. The new CPRA was officially launched on April 13, 2023, at the Manila Hotel before members of the legal community.^[25] Part of the event is the introduction of the New Lawyer's Oath, which Senior Associate Justice Leonen himself authored.^[26] The new Oath can be viewed below, as compared to the proposal of SAJ Leonen and the Sub-Committee for the Revision Of the Code:

REVISED LAWYER'S OATH (A.M. No. 22-09-01-SC: Code of Professional Responsibility and Accountability)

I, (name), do solemnly swear (affirm) that I accept the honor, privilege, duty and responsibility of practicing law in the Philippines as an Officer of the Court in the interest of our people.

I declare fealty to the Constitution of the Republic of Philippines.

In doing so, I shall work towards promoting "the rule of law and a regime of truth, justice, freedom, love, equality, and peace."

I shall conscientiously and courageously work for justice, as well as safeguard the rights and meaningful freedoms of all persons, identities and communities. I shall ensure greater and equitable access to justice. I shall do no falsehood nor shall I pervert the law to unjustly favor nor prejudice anyone. I shall faithfully discharge these duties and responsibilities to the best of my ability, with integrity, and utmost civility. I impose all these upon myself without mental reservation nor purpose of evasion.

[For oaths] So help me, God. (Omit for affirmations)

Proposed Revised Lawyer's Oath SUB-COMMITTEE FOR THE REVISION OF THE CODE OF PROFESSIONAL RESPONSIBILITY

I, do solemnly swear, as an officer of the court, that I will maintain allegiance to the Republic of the Philippines. I shall be loyal to the Constitution, and uphold the rule of law.

I shall embody integrity and practice independence, propriety, fidelity, competence and diligence, equality, and accountability in all that I do. I shall safeguard the rights and meaningful freedoms of all persons, identities and communities.

So help me God.

Proposed Revised Lawyer's Oath JUSTICE MARVIC MARIO VICTOR F. LEONEN

I, (name), do solemnly swear (affirm) that I accept the honor, privilege, duty and responsibility [duties and responsibility] of practicing law in the Philippines as an Officer of the Court in the interest of our people.

I declare fealty to the Constitution of the Republic of Philippines.

In doing so, I shall work towards promoting "the rule of law and a regime of truth, justice, freedom, love, equality, and peace."

I shall conscientiously and courageously work for justice, as well as safeguard the rights and meaningful freedoms of all persons, identities and communities. I shall ensure greater and equitable access to justice. I shall do no falsehood nor shall I pervert the law to unjustly favor nor prejudice anyone. I shall faithfully discharge these duties and responsibilities to the best of my ability, with integrity, and utmost civility. I impose all these upon myself without mental reservation nor purpose of evasion.

[For oaths] So help me, God. (Omit for affirmations)

In December 2020, an impeachment complaint against the AJ Marvic Leonen was filed by a certain Edwin Cordevilla, who claimed to be the Secretary General of the Filipino League of Advocates for Good Government, represented by lawyer Larry Gadon. The complaint alleged that SAJ Leonen has been “incompetent and negligent” for failing to dispose 37 cases within the required period of disposition. Furthermore, it accused SAJ Marvic Leonen of lacking integrity for not filing his SALN for 15 years.^[27]

Under the 1987 Constitution of The Philippines, grounds for impeachment include: culpable violation of the Constitution, treason, bribery, graft and corruption, other high crimes, or betrayal of public trust. Leonen, being an impeachable official, was accused on the grounds of culpable violation of the Constitution for failing to resolve the cases within the required reglementary period, and betrayal of public trust for not filing his SALN.

Although the trial was certain to take place the following year, the then accused AJ Leonen gained support from the public especially from the legal and academic community. On December 10, 2020, the UP College Of Law released a statement to dismiss the impeachment complaint against Associate Justice Marvic M.V.F. Leonen.^[28] The community believes that Leonen “has expressed consistently, in his decisions and dissents, a commitment to academic rigor, principled discourse, creative expression, and courageous authenticity”. Furthermore, they believe that the act was “a latest assault to send our nation further down the dark road, especially while a global pandemic still hangs over all our heads and threatens to bring our society into despair and destitution”. To add, the Senator Risa Hontiveros also released a statement calling the impeachment unnecessary and counterproductive, where it is only a “distraction that will only drag lawmakers and the public into a pointless political fiasco” in the middle of the ongoing pandemic.^[29]

On 27 May 2021, the Impeachment hearing began and the 44 lawmakers immediately found that the complaint lacked sufficient and valid evidence.^[30]

Under the Philippine Rules of Court, “a witness can testify only to those facts which he knows of his personal knowledge; that is, which are derived from his own perception, except as otherwise provided in these rules (Section 36 of Rule 130)”. In this case, they used supporting documents that were either photocopies or newspaper articles that evidently do not manifest personal knowledge or authentic records, therefore proving the case as groundless.

The then AJ Leonen released a statement via his Chambers, which he then posted on his Twitter account ^[31] expressing his thankfulness for the support from fellow lawyers, professors, and other workers in the Judiciary. He further added that we must courageously focus on the essentials, that we must do what is right at the right time in the right way, and to serve the people well.

Senior Associate Justice Marvic M.V.F. Leonen is active on public speaking and gives public speeches on Philippine law and other related causes. He is often invited to give motivational speeches on public and academic events such as graduations and oath-takings. Among his popular talks is the one he delivered at TEDxDiliman in 2013,^[32] persuading the public on why lawyers matter. The transcription can be read below:

"I suspect I should ask more sympathy from you, one because I'm following Joey Ayala, who probably did an illegal act here. [crowd's laughter] Probably lang, we would have to discuss that in the Supreme Court [crowd's laughter].

And second is that I was given a very difficult task which is in the next 18 minutes, I have to convince you that lawyers matter; [crowd's laughter]And, well, I'm used to very difficult task, you know- talking with the largest insurgent group in the country and asking them to sign a framework agreement that's very difficult that it took me two years, not 18 minutes. But in any case, I'd like to start with 1979 when I entered the University of the Philippines knowing that's what I wanted to do was to become a lawyer. I entered the portals of this; College- the School Of Economics. And at that time we were only starting to discover that Martial Law was not what it was meant to be; that there were there was pervasive poverty all around; and human rights violations were happening. I entered the UP College of Law in 1983 in the following year- Ninoy Aquino was shot, Lean Alejandro was assassinated and we were on the streets walking and asking that the dictator to come down. And of course, at that time, we saw that the law was not, also, what it was meant to be.

I became a FLAG lawyer, I joined the free legal assistance group, and one of the first cases that were given to me, was a raid of a shanty in Novaliches and they found some firearms over there and they asked me to do the impossible, which was to try to have the persons acquitted of Illegal Possession Of Firearms. But they had firearms, and so, I thought, "Is this what what the lawyer is supposed to be?". So I thought to myself, "What should I do?" Then I remember Constitutional Law Article 3 Section 2, "The right of the people to be secure in their persons, places, papers and effects against unreasonable searches and seizures shall be inviolable. And no search warrant or warrant of arrest shall issue except upon probable cause to be determined by the judge after particularly describing the place", Wait a minute, quote and quote, "after particularly describing the", Hindi UP kasi ako kaya alam ko yun; [crowd's laughter], "...after particularly describing the place to be searched", Wait a minute! I looked up the warrant- unnumbered shanty! So I moved to quash and move to exclude evidence. It was granted. My clients were acquitted. They were NPA people but now they rejoined Society.

So that was one of my first successes as a lawyer. And buoyed by that, inspired by that, we thought that law mattered for people for whom law is very real. So what we did was set up the Legal Rights and Natural Resources Center. We scoured the country, work with Indigenous' Peoples Groups, went up mountains- Mount Apo several times- six times, I think, with Joey Ayala. And then we found out that there was a commercial, geothermal power plant that was about to be constructed, right at the heart of the ancestral domain of the Bagobo. So what did we do as lawyers? We crafted the 57-page petition, which we thought was very creative. First and foremost, it was a protected area. And at the middle of the protected area, they were going to put a commercial project. A commercial geothermal power plant and we thought arguing that, in a protected area in the concept of the law, in the idea of what the protected area was, as we imported from developed countries- there should be no commercial activity inside, first argument.

Second argument. This was the first and environmental impact statement assessed by the DENR and we thought that it was high time because there was Section 16 of Article 2 of The Constitution that the rhythm of harmony and nature required that the Court extended its judicial review more strictly into administrative cases coming from the DENR, so that not only substantial evidence could be examined but they would look up the use of science in terms of the environmental impact statement. Very good arguments. Very brilliant, very creative. It is so we filed it with the Supreme Court, and the Supreme Court issued, a one-page decision dismissing our case outright without even asking the respondents to file a comment. But undeterred because we have faced the community, we have faced a civil society, we were faced an entire movement wanting to prevent the invasion of Apo Sandawa or Mt. Apo at that time, we filed a motion for reconsideration. Again, arguing the same point, but citing more law journals and more jurisprudence on our side. The motion for reconsideration was longer than the petition. And finally the Supreme Court again, came out with a one-page decision. This time in one paragraph. It says, "Dismissed. No substantial argument raised". And that was our case in Mount Apo. But we did not lose heart because we saw that the law has to be argued at the right time.

So that in some time in the year 2000, faced with the community that was saying that it was facing the largest mining concession ever awarded in this country 95 thousand hectares. As far as your eye can see, is 400 hectares on all ends. 94,000 struggles for provinces in Mindanao. So what we did for them was craft a petition, which was entitled La Bugal Tribal Association vs DENR. Our argument was very simple: The constitution of the Republic of the Philippines in Article 12 Section 4 said: only financial, either financial or technical assistance agreement would be allowed to any fully owned foreign concession in this country. This was a change from our Old Constitution. Now, this concession that's fully owned, but they operated they would manage they would provide financial assistance and technical assistance. It was an "and" and not an "or". So we filed with the Supreme Court arguing our case. That the intension of The Sovereign people expressed in the Constitution was to declare this law as unconstitutional. January 2004 with the majority of 8-for 6-against and 1 taking no part Supreme Court of the Republic of the Philippines.

Declared that the first FPAA in this country. The first largest fully foreign owned mining concession in this country was unconstitutional, null and void ab initio. We celebrated, we went up the mountain. We told our people that this is how the law moves. This is your Constitution. You are part of the Republic of the Philippines. But then, there was a motion for reconsideration that was filed and the motion for reconsideration was heard by the Supreme Court. No less than two retired justices arguing for the Chamber Of Mines and we argued as best as we could, I stood there for eight hours in front of the Supreme Court en banc and they stood there for a light number of hours arguing their case. By December of that same year, the vote was 10–4–1, and we lost the case. It was reversed in a span of 11 months, the Supreme Court, read that provision in a different way. And we had to go up to the community to explain to them why you law still mattered, and it was a difficult way to explain to them.

That is what the law is. Sometimes it is for you. Sometimes, it's against you.

But why does why does the law matter and why you lawyers matter? For simple reason, first is because the law is real. Because there is a law, police can come to get you. You will be caught for color coding, you will be arrested for some kind of an offense, including singing the National Anthem in the wrong way [crowd's laughter]. I'm just saying; [crowd's laughter]. So, Popo is a lawyer[crowd's laughter]; [crowd's laughter], maraming huhulihin kayo lahat, di ako nakinig di ako kumanta di ako kasama [crowd's laughter] . The law is real for people who need the law. For instance, a daughter that is raped by a father 11 times. We just made that ruling a week ago. The law is real for people who need to go against a tax person who is asking them to pay more than what they do. Therefore, you will need lawyers.

Second reason that lawyers matter is that because the law evolves. Before when we fired the Mount Apo, our case there was no Writ Of Kalikasan. Now, there is one- lawyers drafted it. Before when we were counsels to the families of involuntarily disappeared, all we had was a Writ Of Habeas Corpus. Today, you can have a Writ Of Amparo and more than that. You can have the Writ Of Habeas Data. Before we cannot argue Ancestral Domain. Today, you have the Indigenous Peoples Rights Act. Before you cannot argue environment. Today, you can, you can get a Writ Of Kalikasan in any of the levels of our court and we have issued a Writ of Kalikasan on for several projects in the Court. Lawyers will help you adjust the law in order that of course more people will be assisted and of course in order to balance the needs of our country for commercial development and the need for our country for soldiers, social justice. The third reason that lawyers matter is because the law helps us understand ourselves. Sure. There are concepts of property, which defines who to us is an agricultural tenant, and who is a land owner. But our concepts of property; also say, that property is about social justice. That property can be limited. Hence, you have limitations on your exercise of property taking into consideration the environment.

We have nuisance provisions in the law and you have provisions both in treaty and in the law saying that in times of War, whether it be of full-blown Wars between two states, or wars of are known as armed conflicts of a non-international character, such as what happened in Zamboanga, that civilians are to be protected. They tell us that civilians are important. Of course, we still have to struggle because laws evolve.

Men can only commit adultery, women can, ah, concubinage, I'm sorry, women can only commit adultery. Prostitutes are criminals. We have, we still have a lot to do. The only way that you can separate from your spouse. Well, one of the ways that you can separate from your spouse; [crowd's laughter]. Believe me. I've experienced in this; [crowd's laughter], the only way that I, one of the things that you can separate from your spouse is to actually prove the condition called "psychological incapacity", a concept of only one religious sect within our country and not of all, but still this law exists. They can evolve, they tell us who we are. And therefore, it is important that we are lawyers who understand you, and therefore try to change it. So that how we constitute ourselves, how we understand our identity is there. And by the way, Bangsamoro will be soon a law, not a minority, but one of the legitimate identity within our country.

And the fourth reason I think most important that lawyers matter is because lawyers are a luxury. You only go to lawyers in times of need. Unless they are your friends in which case you have drinks with them, not because they're a lawyer, they start talking about the law. They start becoming boring [crowd's laughter]. But normally, you would want to go to a lawyer only when you are at the end of your rope. When you are actually faced with time in prison, when you are actually faced with an assessment from the BIR. When you're actually faced with the need to settle your domestic resources, when you're actually faced with conditions, like a mining company entering your ancestral domain.

Here is an example of a situation which was caused by a lawyer: a lawyer got a TRO to stop a mining firm from entering mountains in Nueva Vizcaya. And she was a very diminutive individual, very petite, but she was able to get a writ in order to stop a mining company there. You would certainly go to a lawyer at that time.

Hence, lawyers matter because they will hold your hand. Because they are the ones that should attend to you with compassion, because they are the ones who will sit with you, in your times of trouble. Even with your spouses, even with your enemies. They are the ones who will be there and you will stick with you, hopefully with or without the payment of attorney's fees [crowd's laughter] until the very end. And because they need to be there. Therefore, lawyers matter.

We need lawyers. We need good lawyers. We need lawyers who understand that they are not a joke. We need lawyers to understand that their careers are not careers. It is a profession. It is a passion and I tell you that is why lawyers matter.

I am Marvic Leonen. I am a lawyer."

In addition to his TED talk, other notable talks include his view about Reification,^[33] his Bar 2019 Oath-taking speech,^[34] and his 2020-2021 Oath-taking speech delivered to the batch of successful examinees whom he served as their Bar Chairperson.^[35]

Leonen is divorced (having been once married to an Australian national of Filipino and Spanish descent) and has one daughter, Lian Laya (nicknamed "Malaya" or "free").^[36] Leonen and his former spouse have been actively co-parenting Lian Laya since 2004, making sure he is always present in every stage of her life. He revealed in a 2013 interview with Ces Drilon that being a father is what he would swap for his job.^[37] Leonen maintains a following among law students and the youth, often posting jokes on love and beliefs based on his favorite books on Twitter as well as in graduation speeches and socio-political forums.^[38]

Leonen is a vegan since 2017 and is an active advocate of plant-based diet as a principled choice to consume ethically and ecologically^[39] and is highly against animal-sourced products because he believes that they contribute to global warming and overall destruction of the ecology.^[40]

Leonen is also a fountain pen aficionado and advocate, often attending fountain pen events in Manila^[41] and does photography (often street photography) as a hobby, maintaining an Instagram account to showcase this hobby.^[42] He is fluent in Filipino, English, and Ilocano. Around his right wrist, he has a Cordilleran-inspired tattoo depicting a lizard, with designs featuring combinations of snake and centipede symbolisms (called "tinulipao", "tab-whad", "inang-oo" and "gayaman").^{[citation needed]}