At least 50% of UK environmental law derives from the EU. It has driven improvements in environmental standards and some sectors welcome a degree of cross-EU regulation and its ability to establish a level playing field amongst competitors in the EU market. It is also an enabler of the EU clean technology and environmental services industries.

If the UK remained part of the EEA upon exit from the EU, it would continue to be bound by most EU environmental law but would cease to have a vote in Council on its creation or amendment. The UK may retain some ability to influence but it is likely to be less.

In other circumstances, the UK would not be bound by EU environmental law, unless it agreed otherwise as part of a deal to secure continued access to the Single Market. However, it is unclear whether the UK as a whole, or devolved administrations separately (having competence for environmental regulation in their parts of the UK), would seek to remove it from the statute book. EU regulation implementing international treaties would be likely to remain untouched if the UK is individually a party to the relevant treaty, or alternatively the UK may choose to become party. Particular areas of EU regulation where the UK has struggled to comply such as air quality targets, or which are very burdensome such as waste law and chemicals registration, may be early targets to remove. Even in the event of a significant reduction in UK regulation, UK exporters would continue to be obliged to meet EU environmental and safety products standards in order to sell into the EU market. Any reduction in standards of environmental protection could also meet with public opposition and industry may choose to continue to voluntarily apply the EU standards to avoid reputational issues.

Major elements of the UK's environmental law of domestic origin would be unaffected, including liability for clean-up of contaminated land and requirements for most environmental permits, e.g. water discharges and abstraction. Criminal liability for breach of offences often involving strict liability and the possibility of tort liability arising from environmental pollution are notable features of the UK system that would remain untouched.