The climate crisis, a problem that once took the form of abstract temperature charts and projections, is now a dizzying parade of broken meteorological records and natural disasters. It therefore seemed like apt timing when, in June, the Stop Ecocide Foundation’s (SEF) expert drafting panel released its definition of the crime of 'ecocide'.

Josef Rybacki

Josef Rybacki

Currently under the Rome Statute of the International Criminal Court (ICC), there are four crimes, including genocide. SEF is an NGO that advocates amending the statute to add ecocide as a fifth crime. The publication of the proposed definition is an important step towards achieving that goal.


[U]nlawful 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.

Actus Reus

There are two types of act that form gateways to criminal liability under the definition. Firstly, 'unlawful' acts. Although there will be inconsistency in what constitutes illegality at a domestic level, this is the more straightforward route, as the prosecutor can simply point to the domestic law breach. Under this gateway, officers of a car company convicted of an emissions fraud in violation of national law, for instance, could be guilty of ecocide.

The second gateway is 'wanton acts'. This might, depending on your background, evoke the offence of wanton or furious driving, where it effectively means straight recklessness, or the Rome Statute’s Article 8 definition of war crimes, specifically extensive destruction and appropriation of property. Unsurprisingly, ecocide tacks more closely to the latter. It defines wanton as, 'with reckless disregard for damage which would be clearly excessive in relation to the social and economic benefits anticipated'.

This gateway poses a more difficult route. The word 'clearly' creates a high bar for the prosecution. Defendants will argue about their knowledge (or ignorance) of the damage or scale of the damage. It will be interesting to see how the court approaches the proportionality test and how, for instance, profit margins are measured against habitat loss.

Mens Rea

The defendant must have had 'knowledge that there is a substantial likelihood of severe and either widespread or long-term damage to the environment being caused by those acts'. The usual mens rea for crimes under the Rome Statute is awareness of a near certainty that the event will occur. Ecocide casts the net more widely – the defendant need only have known that there was a substantial likelihood of the damage occurring.

'Severe' is defined as 'very serious adverse changes, disruption or harm to any element of the environment, including grave impacts on human life or natural, cultural or economic resources'. This part of the definition should help sift ordinary, domestic environmental offences from ecocide.

Not only does the environment cover a range of resources, it is further defined as covering the biosphere (ecosystems), cryosphere (frozen ice and ground), lithosphere (crust and upper mantle), hydrosphere (seas, oceans, lakes etc) and atmosphere (gases), and outer space. If a billionaire space explorer commits an act of ecocide en route to Mars, they will be in scope.

Finally the potential damage must be either widespread or long-term. 'Widespread' means that it extends 'beyond a limited geographic area, crosses state boundaries, or is suffered by an entire ecosystem or a large number of human beings'. The inclusion of 'a large number of human beings' suggests that there will be some overlap with fact patterns that give rise to environmental class actions, for instance water contamination.

'Long term' is defined as irreversible, or that cannot be redressed through natural recovery 'within a reasonable period of time.' This is more likely to be assessed in the context of a human life than, for instance, a geological epoch. The dumping of nuclear waste would probably be caught by this part of the definition.


International criminal law is an imperfect tool for solving broad environmental problems. Issues such as climate breakdown require political and economic solutions. The definition of 'wanton acts' is an ambitious attempt to bring international criminal law to bear on these broad problems. The ICC will have to balance the environmental damage of an activity against its economic and social benefits – a difficult task.

On the other hand, the effects of the climate crisis bear a striking comparison to the effects of war (mass death, destruction, population displacement, etc), the natural domain of the ICC. It is easy to think of cases that would fit squarely and logically into the definition of ecocide, particularly the 'unlawful acts' gateway. Environmental crimes are often international in impact, why should they not be prosecuted at an international level?

A 2019 UN report found that to keep within the Paris Agreement’s global warming limit of 1.5°C, the world must reduce carbon emissions by 7.6% every year from 2020 to 2030. Emissions fell by 5.8% in 2020 and are set to rise by 4.8% in 2021. Meanwhile, the government’s spokesperson for the COP 26 (the UN’s 26th climate change conference) recently wrote 'Nobody will be forced to ditch their gas boiler or diesel car overnight, but in 10-15 years, there will be change.' It’s unclear what kind of world we will be living in in 10 or 15 years, but it could well be one in which the ICC is prosecuting people for ecocide.


Josef Rybacki is an associate in WilmerHale’s UK white collar defence and investigations practice