California became the first state to make stealthing, the act of removing a condom without consent during intercourse, illegal after Gov. Gavin Newsom signed a bill into law on Thursday.

The bill amends the state’s civil definition of sexual battery, making stealthing a civil offense and giving victims the grounds to sue their assailants for damages.

“By passing this bill, we are underlining the importance of consent,” the governor’s office said in a tweet.

Assemblywoman Cristina Garcia, who represents part of Los Angeles County and who sponsored the bill, said the measure would give victims another resource to hold perpetrators accountable.

Ms. Garcia thanked the governor on Thursday for “ensuring that stealthing isn’t only immoral but illegal.”

Ms. Garcia, a Democrat, said that she had tried to pass legislation criminalizing stealthing since 2017, when a Yale University study brought widespread attention to it. She said in an interview last month that she had run into considerable opposition over the years, mostly from lawmakers concerned about what penalties to set, how to prove it had been committed and other issues. The State Assembly unanimously passed this iteration of the bill in September.

The bill does not stipulate the possibility of jail time for stealthing, but supporters of the law say that civil litigation can sometimes yield more results for victims. Last month, Ms. Garcia said the bill was “a good first step” in laying the groundwork to eventually add stealthing to the state’s criminal code.

Stealthing tends to go widely unreported because there were few ways to address it legally, but it is still a widespread issue, according to advocates and research.

A study published in the National Library of Medicine in 2019 reported that 12 percent of women said that they had been a victim of stealthing. Another study that year found that 10 percent of men admitted to removing their condom during intercourse without their partner’s consent.

But Alexandra Brodsky, who wrote the 2017 Yale study and is the author of “Sexual Justice,” a book that addresses various forms of institutional response to sexual harassment and assault, said last month that civil suit remedies were “really underutilized” in such cases.

Ms. Brodsky said that, in contrast to criminal cases, in which prosecutors bring charges and a jury can send a convicted person to prison, civil suit remedies were often more useful to victims

“There are many survivors who do not want to see the person who hurt them in prison and could really use help covering medical debt or could use help having the resources to see a therapistMs. Brodsky said.

Similar bills on stealthing have been introduced in New York and in Wisconsin, but neither has passed.

The governor signed another bill sponsored by Ms. Garcia into law on Thursday, a measure that removes a spousal exemption to the state’s laws on rape.