California Attorney General Jerry Brown blasted the EPA in his testimony before a U.S. Senate committee

The briefing was part of a hearing by a committee, headed by Sen. Barbara Boxer D-Calif., investigating the EPA's denial of a waiver that would have allowed California to enforce stricter greenhouse-gas emissions regulations for vehicles.

"Charged with protecting the environmental trust, the EPA has instead betrayed its sacred mission," Brown said at the hearing in Los Angeles. "The agency's top staff should explain, under oath, why they sabotaged the groundbreaking effort by California and 14 other states to reduce dangerous greenhouse gases emitted by motor vehicles."

Brown's testimony is the latest strike in California's long battle to tighten emissions standards. The fighting began almost two years ago, when California first requested the waiver to enact emissions standards it had passed in 2002.

Since the Golden State made its request, 16 other states -- making up about 45 percent of all U.S. auto sales -- have adopted or are considering adopting California's standards. So the outcome of the battle will affect those states as well.

In November, California sued the EPA to try to force a decision (see California Sues EPA for Greener Vehicles). But in spite of a federal judge upheld a ruling that California has the right to set its own vehicle-emissions standards, the EPA denied the waiver in December (see Judge Upholds California Auto-Emission Law, EPA Rejects California Vehicle-Emission Standards). The agency said greenhouse gases are "fundamentally global in nature," not local, and are therefore the purview of the federal government, not the states.

On behalf of California, Brown sued the agency again this month in an attempt to overturn the decision (see Emission Technologies Could Benefit From Regulation Battle). The Senate committee also is looking into the matter.

In December, EPA Administrator Stephen Johnson turned down an invitation to discuss his decision at the hearing (see The Swamp).

"Rather than looking in the eyes of the people he is affecting, Mr. Johnson is hiding out in Washington, D.C.," Boxer said in a written statement at the time. "His shameful decision denying the California waiver must be overturned."

While the solar industry doesn't stand to benefit directly from California's emission standards, Gary Gerber, president of the California Solar Energy Association and founder of Sun Light and Power, said he supports the state's efforts.

"Anything that frees the state up to have a free reign in improving our carbon footprint is to everyone in the state's advantage," he said,