(Adds details on court ruling, background on rules, litigation)
SAN FRANCISCO, Dec 21 (Reuters) - A second U.S. judge on Thursday blocked President Donald Trump's administration from enforcing new rules that undermine an Obamacare requirement for employers to provide insurance that covers women's birth control.
U.S. District Judge Haywood Gilliam Jr. in Oakland, California, said the federal government likely did not follow proper administrative procedures in promulgating the new rules, and put them on hold while a lawsuit challenging their legality proceeds.
The decision followed a similar ruling from a federal judge in Philadelphia last Friday that blocked the administration from enforcing rules it announced in October allowing businesses or nonprofits to obtain exemptions on moral or religious grounds.
Gilliam ruled on a lawsuit pursued by Democratic attorneys general in California, Delaware, Maryland, New York and Virginia.
He said that a preliminary injunction was necessary given the "dire public health and fiscal consequences" that could result as a result of the administration adopting the rules without the input of interested parties.
"If the Court ultimately finds in favor of Plaintiffs on the merits, any harm caused in the interim by rescinded contraceptive coverage would not be susceptible to remedy," he wrote.
The U.S. Justice Department, which has defended the rules in court, did not immediately respond to a request for comment.
The lawsuit is among several that Democratic state attorneys general filed after the Republican Trump administration revealed the new rules on Oct. 6, which targeted the contraceptive mandate implemented as part of 2010's Affordable Care Act, popularly known as Obamacare.
The rules will let businesses or nonprofits lodge religious or moral objections to obtain an exemption from the law's mandate that employers provide contraceptive coverage in health insurance with no co-payment.
Conservative Christian activists and congressional Republicans praised the move, while reproductive rights advocates and Democrats criticized it. (Reporting by Dan Levine in San Francisco and Nate Raymond in Boston; editing by Leslie Adler and Jonathan Oatis)