The U.S. Department of Justice decided to drop its vindictive investigation into four automakers that teamed up with California to implement stricter emissions standards for cars and light trucks than the Trump administration wants, as The New York Times reported.

In September, the Justice Department decided to investigate Ford, Volkswagen, Honda and BMW for antitrust practices, for their decision to work with California to reject the White House's rollback of national fuel economy standards, as The New York Times reported. Under the Clean Air Act, California has had the authority to protect its citizens from air pollution , but the Trump administration revoked that authority once California struck a deal with the automakers, according to CNN .

Last week, after looking into the matter since September, the Justice Department decided that the automakers' efforts to reduce pollution spewed by their vehicles did not actually violate any laws. The decision not to pursue legal action represents a rare retreat for the Trump administration, which has aggressively sought to dismantle environmental regulations, as CNN reported.

California was the only state to have the waiver from the Clean Air Act that allowed it to set its own emissions standard that was stricter than the national standard. However, other states were allowed to follow California's lead, which some of the most populated states did. In all, 13 states followed California's lead. Those states, plus California, make up 40 percent of the U.S. population, as CNN reported.

California's Governor Gavin Newsom cheered the end of the investigation. "These trumped-up charges were always a sham — a blatant attempt by the Trump administration to prevent more automakers from joining California and agreeing to stronger emissions standards," he said in a statement, as The New York Times reported. He added that the decision is "a victory for anyone who cares about the rule of law and clean air."

The July move by the automakers was initially dismissed by the Trump administration as "a PR stunt that does nothing to further the one national standard that will provide certainty and relief for American consumers," as Car and Driver reported.

At the heart of the issue was a rollback of the Obama-era emissions standard set in 2012 that required a 54.5 miles per gallon for new cars by 2025 — effectively doubling the current standard. The Trump administration rolled the requirement back to 40 miles per gallon. The deal that California struck with the four large automakers will require a fleet average of 51 mpg for cars and light-trucks by 2026, as Car and Driver reported.

After California bypassed the Trump administration's rollbacks, the White House aggressively undermined California's authority and funding. Not only did the administration revoke the state's authority to set its own emissions standard, it then forced California to drop Quebec from its carbon-credit market. Also, in September, the U.S. Environmental Protection Agency threatened to withhold federal highway funding from California, as The New York Times reported.

The deal struck with California will require automakers to build more costly cars. However, there are also some savings since companies that meet the California standard will have to build only one line of cars, instead of one line that meets the California standard and another that meets the national standard, according to CNN.