Two of Breonna Taylor’s aunts watched in Richmond on Monday as Gov. Ralph S. Northam ceremonially signed a statewide ban against police use of no-knock search warrants, a law named after Ms. Taylor, a Kentucky woman who was fatally shot when Louisville police broke down her door in the middle of the night.

“Breonna’s Law” is the first such law enacted by a state since the 26- year-old Ms. Taylor, an emergency medi- cal technician, was killed in March, Gov. Northam said. Two other states — Oregon and Florida — already had similar bans, while several municipalities, including Louisville, have banned the practice since Ms. Taylor was killed.

Ms. Taylor’s death, along with the killing of George Floyd while in police custody in Minneapolis and the police killings of other Black people, sparked massive protests around the county against police brutality and systemic racism. During a special General Assembly session, Virginia lawmakers passed a host of police and criminal justice reforms, including a ban on the use of chokeholds, a requirement that police officers intervene to stop the use of excessive force by another officer, and changes that make it easier to de-certify officers who commit misconduct.

“We’re here today because when the country saw what happened in March, people said, ‘That’s wrong. You need to do something,’ ” Gov. Northam said of Ms. Taylor’s killing.

Attorney Benjamin Crump, who is representing the Taylor family, also attended the signing ceremony. He thanked Gov. Northam and the lead sponsors of the legislation, Sen. Mamie E. Locke of Hampton and Delegate Lashrecse Aird of Petersburg, both members of the Virginia Legislative Black Caucus, for “helping to make a more just society, a more just America, one where Breonna Taylor gets to sleep in peace without the police busting in her door.”

Ms. Taylor’s aunt, Bianca Austin, said no-knock warrants are “detrimental and destructive to Black lives.”

“Thank you for listening to our voices,” Ms. Austin said. “We hope this encourages other states to get on board” in banning no-knock warrants.

The law, which goes into effect in March, prohibits police from going into a home without first announcing themselves. It also requires that search warrants be served only during daylight hours unless police can show a magistrate or a judge good cause as to why the warrant needs to be served at night.

The law does not apply to search warrants seeking to take a blood sample from someone; they can be served anytime.

Ms. Taylor was fatally shot when police executed a no-knock warrant at her Louisville apartment after midnight on March 13. Police said they did knock and announce themselves before using a battering ram to get inside.

Ms. Taylor’s boyfriend, Kenneth Walker, who was there at the time, said he thought intruders had burst into Ms. Taylor’s home, not police. Mr. Walker fired his gun once, striking one officer in the leg. Ms. Taylor was killed when police returned fire.