Section 702 of the Foreign Intelligence Surveillance Act, or FISA, allows government agencies to collect information about foreign nationals located abroad. That surveillance can happen without a warrant and the government can order email providers to turn over any messages of a particular foreigner, including those with a U.S. citizen.

Section 702 is set to expire this week. President Donald Trump has called for its extension, but there are Congressional lawmakers in both parties who oppose the kind of surveillance the law allows for. Elizabeth Goitein at the Brennan Center for Justice has testified before Congress advocating for reform of the law. She says right now it lets agencies search through Americans’ sensitive data.