SACRAMENTO, Jan. 2 (UPI) -- California filed suit Wednesday against the U.S. Environmental Protection Agency for blocking the state's tailpipe greenhouse gas emissions standards.

In a suit filed in federal court, California Attorney General Jerry Brown challenged the EPA's denial of California's request to implement its emissions law requiring a 30 percent reduction in motor vehicle greenhouse gas emissions by 2016, the attorney general's office said in a news release. Fifteen other states also are challenging the EPA.

"The denial letter was shocking in its incoherence and utter failure to provide legal justification for the (EPA) administrator's unprecedented action," Brown said.

Under the 1963 federal Clean Air Act, California is allowed by waiver to impose environmental regulations that are stricter than federal standards because of the state's "compelling and extraordinary conditions," including topography, climate, and high number and concentration of vehicles, Brown said.

In denying the state's waiver request, the federal EPA, among other things, said federal energy legislation passed and signed into law in December increases vehicle fuel efficiency so much as to make the waiver unnecessary.