Environment advocacy groups are suing the US government over its decision to withdraw a key 2009 climate change ruling, the “endangerment finding” which had established that greenhouse gases pose a risk to public health and environmental safety. The ruling, which allowed the EPA to implement many regulatory policies aimed at reducing climate change, was rescinded by US President Donald Trump in February. The lawsuit alleges that the decision will risk the health and welfare of US citizens and result in more pollution, higher costs, and avoidable deaths. The decision is part of a series of steps by Trump to prioritise deregulation, increase fossil fuel production, and reverse climate regulations. However, experts suggest that long before Trump, decades of US policy have been harmful to the environment.