Two transgender Kansans asked a state judge Friday to strike down a new law that abruptly invalidated the driver’s licenses of residents who had changed their gender designations.

The law, which took effect Thursday, requires the gender marker on a driver’s license to match a person’s sex at birth.

The law also invalidates the birth certificates of residents who had changed the document to reflect their current gender identity and allows private citizens to seek financial damages from transgender Kansans who use a bathroom that does not match their sex at birth.

In their lawsuit, the plaintiffs have requested a temporary restraining order and a temporary injunction to stop the state from enforcing the law while the case is being decided.

The measure “is a cruel and craven threat to public safety all in the name of fostering fear, division and paranoia,” Harper Seldin, a senior staff attorney for the American Civil Liberties Union, said in a news release.

The plaintiffs, who are suing under pseudonyms, have been living as men for many years and have driver’s licenses that say they are men. Many transgender Kansans received a letter this week from the Kansas Department of Revenue notifying them that the Legislature had not included a grace period for updating credentials.

“Your current credential will be invalid immediately,’’ the letter said. It then directed recipients to “surrender your current credential” and exchange it for one that reflects their birth sex. Driving without a valid license, it noted, could result in other penalties.

About 1,700 driver’s license holders in Kansas are affected by the new law, according to state officials. Transgender people age 13 and older account for about 1% of the U.S. population, according to the Williams Institute, a demographic research center at UCLA.

Lawyers with the ACLU filed the lawsuit in Douglas County. The plaintiffs claim that the law violates several provisions of the state constitution, including the right to due process and personal autonomy. They argue that because other Kansas drivers can choose how they are represented on their license, the law violates their guarantee of equal protection.

“By forcing trans people, and only trans people, to have a license that says ‘F’ when they live their lives as men or vice versa for trans women, it is requiring them to convey the state’s belief that transgender people don’t exist,” Seldin said.