Making Ecocide an International Crime: A Discussion with Kate Mackintosh and the Human Security Law Center


By Rachel Toni Sleiman, William & Mary Law School ’23 (see full bio at end of article).

On Tuesday November 23, 2021, Professor Nancy Combs and the Human Security Law Center at William & Mary Law School hosted a presentation by Kate Mackintosh, the inaugural Executive Director of the Promise Institute for Human Rights at the University of California-Los Angeles School of Law, about recent efforts to establish ecocide as an international crime and in particular as the fifth international crime within the jurisdiction of the International Criminal Court (ICC).

Mackintosh discussed with the audience how she became involved in the effort to criminalize ecocide, what the process of developing a legal definition of ecocide entailed, and where the path to establishing a new international crime may lead.

Originally from England, Kate Mackintosh spent twenty years in the Netherlands, where she worked in the development of international criminal law and held various roles in international criminal tribunals.  It was there that, around 2014 or 2015, while heading the International Criminal Tribunal for the former Yugoslavia (ICTY)’s operations, Kate Mackintosh attended a presentation led by a wildlife campaigner who spoke to international court personnel about the harms inflicted by wildlife crime.  The campaigner highlighted crimes committed ­by individuals–particularly in East Africa–that threatened the survival of animals, including elephants and rhinoceroses, both of which were already endangered.  Was there anything in international criminal law that could hold these perpetrators accountable to such crimes?

The Rome Statute was ratified in 1998, creating the ICC and providing it jurisdiction over four core international crimes, considered “the most serious crimes of concern to the international community as a whole:”[1] genocide, crimes against humanity, war crimes, and the crime of aggression.[2]  The primary objective of the ICC is to help put an end to impunity for the perpetrators who committed these crimes–which hinder the peace and security of individuals and groups of people–and thus to contribute to the prevention of future atrocities.  The harms the wildlife campaigner described were crimes committed against animals or the natural environment–neither of which aligned specifically with the goals underlying the four core international crimes.  Yet, Mackintosh described an a-ha! moment at the wildlife presentation that motivated her involvement in defining ecocide as the fifth international crime: framing the harms the wildlife campaigner spoke of as a crime against the human environment.

In support of this mission, Mackintosh became involved with a growing movement which culminated with her joining an expert drafting panel commissioned by Stop Ecocide International in 2021,[3] at the request of members of the Swedish Parliament.  Working with eleven other international criminal and environmental lawyers from around the world over a period of six months, Mackintosh and the panelists drafted a proposed amendment to the Rome Statute that defined a new international crime of ecocide and included it as the ICC’s fifth international crime.  The new definition is not limited to armed conflict related damage and was also distinguishable from, and yet in line with, the purpose of the four other international crimes.[4]

During this time, Mackintosh also discovered that the seemingly novel concept of ecocide actually dated back at least fifty years–first being used in 1970 to describe the devastating effects of the herbicide Agent Orange used by the United States during the Vietnam War.[5]  The idea of ecocide later expanded beyond wartime destruction to include acts involving industrial pursuits,[6] foreshadowing today’s concerns about our environment.

The shaping of ecocide, and the advocacy by private organizations over the past half-century, clearly influenced the expert panel’s definition, which was officially unveiled in June 2021.[7]  The proposed amendment defines the crime of ecocide as “unlawful or wanton acts committed with knowledge that there is a substantial likelihood of severe and either widespread or long-term damage to the environment being caused by those acts.”[8]  During her presentation, Mackintosh detailed three significant aspects of the definition that were crucial to the expert panel in drafting this definition of ecocide, which notably applies to acts committed in both wartime and peacetime.

First, the panel felt it important to not limit the definition of ecocide by defining criminal behavior as “unlawful or wanton.”  Mackintosh explained that the panel deliberately did not define the term “unlawful” so that judges would be free to reference national law in assessing inadequate enforcement of the law by individuals.  The panel added the term “wanton” to render the definition broad enough “to encompass acts that have not yet been prohibited but which we feel must be prohibited in order to protect the environment adequately” from excessive destruction that has no useful social or economic benefit.[9]  Mackintosh emphasized that the addition of “wanton” also serves the principle of sustainable development–the bedrock principle of international environmental law–that “respects not only the rights of current generations, but the rights of future generations.”[10]

Second, Mackintosh noted that the panel sought to mitigate the timing and burden of prosecuting ecocide, which resulted in the clause “committed with knowledge that there is a substantial likelihood.”  Mackintosh emphasized that the crime of ecocide’s threshold is a knowledge of substantial risk that environmental damage would occur.  This provision allows the ICC to move forward with the investigation and prosecution of a crime without waiting for the environmental damage to actually manifest.  In addition, this language does not necessitate that the prosecution proves a direct causal link between the alleged criminal conduct and the damage that has occurred or will arise.

Third, the panelists’ desire to ensure that the definition was holistic and reasonable drove their decision to include a clause requiring “severe and either widespread or long-term damage.”  To honor the holistic meaning of our natural environment, “severe” damage is defined to take into account “grave impacts on human life or natural, cultural, or economic resources.”[11]

In addition to being severe, the damage must be either widespread or long-term.  Here, the panelists forged a compromise between the terminology of two prior definitions of ecocide that stemmed from the late 1970s.  The 1977 Additional Protocols to the Geneva Convention (Protocol I) added the duty of states “to protect the natural environment against widespread, long-term and severe damage” in warfare.[12]  Soon thereafter, in 1978, the United Nations (UN) Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques (ENMOD) entered into force the prohibition of state parties from “engag[ing] in military or any other hostile use of environmental modification techniques having widespread, long-lasting or severe effects as the means of destruction, damage or injury to any other State Party.”[13]

Mackintosh explained that the panel believed the 1977 Additional Protocols’ standard was too high.  If all three effects–severe, widespread, and long-term–had to be met for an individual to be held criminally liable for ecocide, then environmental destruction that should be prosecuted would be immune from prosecution.  For example, certain instances of mass pollution would fall outside the scope of ecocide, because some massive pollution is severe and widespread, but able to be redressed and therefore not be considered long-term.  Therefore, the panel’s treatment of “widespread” and “long-term” as alternative elements allows massive pollution and other types of severe damage to fall within the proposed definition of ecocide.

So, where do we go from here?  “We need to find a party or parties to the Rome Statute to propose our amendment to the other state parties,” explained Mackintosh.  Then, if a member party submits the proposal, a simple majority of the parties to the Rome Statute is required to move forward with discussion of the amendment.  The proposal will then go to the Committee on Amendments, where the draft the expert panel created would likely change.  Once the Committee on Amendments finalizes the amendment, it will be presented back to the States.  A vote in favor of the amendment by two-thirds of the member parties is required to secure its adoption.  Even if the amendment is adopted, however, it is possible that not all state parties will ratify the amendment.  Similarly, “not all important states are parties to the International Criminal Court,”[14] and thereby outside its jurisdiction.

Nonetheless, as attention on the protection of the environment heightens across the globe, Mackintosh hopes that the proposed codification of the crime of ecocide will not only lead to its inclusion as the fifth international crime but also integrate with countries’ own criminal statutes.  Mackintosh emphasized that the goal of her work with Stop Ecocide International and team of expert panelists was always to start the conversation around criminalizing ecocide at the ICC. With increasing attention by countries, corporations, and the general global population to the prospect of individual criminal liability for crimes of ecocide, this goal has already been advanced by facilitating discussion about how to improve industrial and military practices and prevent individuals and corporations alike from committing ecocide.  To learn more, visit Stop Ecocide International.[15]


About the Speaker

Kate Mackintosh is the Executive Director for the Promise Institute for Human Rights at University of California-Los Angeles School of Law.  Mackintosh, a veteran human rights lawyer with more than twenty years of experience in the field, served in various roles at international criminal tribunals in The Hague, including as Deputy Registrar of the International Criminal Tribunal for the Former Yugoslavia (ICTY) and as legal officer at the ICTY, the International Criminal Tribunal for Rwanda, and on post-conflict situations in Bosnia and Herzegovina, Rwanda, and South Sudan.  Mackintosh also worked with Médecins sans Frontières (Doctors Without Borders) for eight years in various roles providing legal and policy advice and leading advocacy initiatives in support of vulnerable populations.  Mackintosh has authored numerous articles and reports, including on behalf of organizations such as UNICEF, the UN Office for the Coordination of Humanitarian Affairs, and Harvard University.

About the Human Security Law Center

The Human Security Law Center (HSLC) at William & Mary Law School centers on human rights, national security and international criminal justice and law.  Its purpose is to provide students with an understanding of and appreciation for national security and human rights issues, particularly through the interplay between national defense and the protection of civil rights in both the domestic and global spheres.  The Director of the HSLC is Ernest W. Goodrich Professor of Law Nancy Combs.

About the Author

Rachel Toni Sleiman is a 2L at William & Mary Law School and a Managing Editor of the Comparative Jurist.  Rachel is also involved as a staff editor on the William & Mary Bill of Rights Journal, research assistant to Professor Nancy Combs, and Student Bar Association Graduate Council representative.  As a law student, Rachel had the incredible opportunity to intern for the Honorable J. Michelle Childs of the District of South Carolina in the summer of 2021, and she plans to intern for the Federal Public Defender’s Office in Columbia, South Carolina, this coming summer (2022). Before coming to law school, Rachel worked as a paralegal specialist supporting the U.S. Department of Justice’s Criminal Fraud Section, where she mainly handled health care fraud litigation.  Rachel hopes to pursue a career in litigation, and her education and experiences, which include majoring in International Studies and Anthropology at Case Western Reserve University and a semester studying abroad in Amman, Jordan, inspired her pursuit of a career in transnational law and human rights.


[1] Rome Statute of the International Criminal Court, pmbl, July 17, 1998, 2187 U.N.T.S. 3 [hereinafter Rome Statute].

[2] Rome Statute, art. 5.

[3] The Stop Ecocide campaign was co-founded by current Executive Director Jojo Mehta and the late Polly Higgins–a UK barrister, author, and visionary who spent the ten years before her untimely passing in 2019 dedicated to propelling ecocide to the forefront of conversation in the international law and international criminal law spheres.  Who We Are, Stop Ecocide Int’l, https://www.stopecocide.earth/who-we-are- (last visited Dec. 22, 2021); Polly Higgins, Stop Ecocide Int’l, https://www.stopecocide.earth/polly-higgins (last visited Dec. 22, 2021). 

[4] The Rome Statute does criminalize as a war crime act that results in the “widespread, long-term, and severe damage to the natural environment.”  Rome Statute, art. 8(2)(b)(iv).  Yet, the state parties involved in the drafting of the treaty included an additional threshold assessment of proportionality between the damage and the anticipated military advantage gained as a result.  Id.  Therefore, under the Rome Statute in its current form, accountability for ecocide is limited–not just to harms incurred during armed conflict but also by military advantage.

[5] Biologist Arthur Galston, who discovered the chemical dioxin that made Agent Orange so deadly, coined the term “ecocide” in a speech calling to ban destructive chemicals at a conference on war and national responsibility in Washington, D.C., in 1970.  David Zierler, The Invention of Ecocide: Agent Orange, Vietnam, and the Scientists Who Changed The Way We Think about the Environment 15 (2011).  The United States utilized the herbicide for defoliation and crop destruction in counterinsurgency operations against the Vietnamese in South Vietnam and across its borders with Laos and Cambodia “to deny the guerilla forces of the [National Liberation Front (NLF)] food and forest cover, protect American soldiers from ambush, and destroy any agricultural areas thought to be under NLF control.”  Id.  Agent Orange is considered to have caused an “abnormally high incidence of miscarriages, skin diseases, cancers, birth defects, and congenital malformations” among the Vietnamese population as well as cancers and other health disorders in servicemen who suffered long exposure to Agent Orange in Vietnam.  Agent Orange, Encyclopedia Britannica (Sep. 22, 2020), https://www.britannica.com/science/Agent-Orange (last visited Dec. 22, 2021).

[6] A broader definition of ecocide arose in 1973 through the efforts of Princeton University Professor Richard Falk whose proposal for an international convention on the crime of ecocide resulted in the first legal definition of the term.  Zierler, supra note 5 at 25, 199 n.26.

[7] E.g., Haroon Siddique, Legal Experts Worldwide Draw Up ‘Historic’ Definition of Ecocide, The Guardian (June 22, 2021),https://www.theguardian.com/environment/2021/jun/22/legal-experts-worldwide-draw-up-historic-definition-of-ecocide.

[8] Independent Expert Panel for the Legal Definition of Ecocide Commentary and Core Text, Stop Ecocide Int’l (June 2021), https://static1.squarespace.com/static/5ca2608ab914493c64ef1f6d/t/60d7479cf8e7e5461534dd07/16 24721314430/SE+Foundation+Commentary+and+core+text+revised+%281%29.pdf [hereinafter Independent Expert Panel].

[9] Kate Mackintosh, Exec. Dir., Promise Inst. for Human Rights, Presentation at William & Mary Law School for the Human Security Law Center: Making Ecocide an International Crime (Nov. 23, 2021).

[10] Mackintosh, supra note 9.

[11] Independent Expert Panelsupra note 8.

[12] Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) art. 55, June 8, 1977, 1125 U.N.T.S. 3.

[13] Convention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniques, art. I, Dec. 10, 1976, 31 U.S.T. 333, 1108 U.N.T.S. 151.

[14] Mackintosh, supra note 9.

[15] Citation for Cover Image: Legal Definition of Ecocide, Stop Ecocide Int’l, https://www.stopecocide.earth/legal-definition (last visited Dec. 22, 2021).

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