This year marks the 20th anniversary of the Sept. 11 attacks and the U.S. government’s subsequent “war on terror.” As part of this war, the government has engaged in extensive military operations abroad.

While attention is currently focused on its withdrawal from Afghanistan, we must note that in prosecuting its war on terror, the U.S. government has also massively expanded its powers at home. While these powers have been adopted in the name of protecting people and freedom in America, they also pose a threat to our liberty. The anniversary of the attacks offers an opportunity to take stock of these long-lasting government powers.

Less than two months after the attacks, Congress passed the PATRIOT Act, which expanded the government’s domestic surveillance powers, including the power to review information about people that is held by third parties. It also weakened Fourth Amendment protections related to “trap and trace” searches, in which incoming phone calls to a person are recorded. In addition, President George W. Bush issued an order to ease the constraints imposed by the Foreign Intelligence Surveillance Act (FISA) on the National Security Agency (NSA). This allowed the agency to execute warrantless searches of American citizens’ emails and phone calls.