The US Postal Service is facing more than just stern warnings over its decision to buy mostly gas-powered mail delivery trucks. Environmental activist groups (including the Center for Biological Diversity and the Sierra Club) and 16 states have filed lawsuits in California and New York State to challenge the Postal Service's Next Generation Delivery Vehicle purchasing decision. They argue the USPS's environmental review was flawed and illegal, ignoring the "decades of pollution" the combustion-engine trucks would produce. The USPS allegedly violated the National Environmental Policy Act by committing to buy 165,000 delivery vehicles (just 10 percent of them electric) without first conducting a "lawful" environmental review. The service only started its review six months after it had signed a contract, according to the California lawsuit.