The Massachusetts Bay Transportation Authority (MBTA) will start randomly inspecting bags on the public transit system in an attempt to deter terrorist acts, Governor W. Mitt Romney announced yesterday.

MBTA officials will use equipment that can detect any trace of explosive material on a bag, such as on seams, zippers, or handles. The tests can be conducted in under a minute, according to a statement from the Governor’s office.

In most cases, officials will not actually open passengers’ bags, though they may request to do so, the statement said.

In addition, “impact teams” trained in anti-terrorism and behavioral recognition will patrol the stations.

“We are fighting a war against people who have as their objective the overthrow of the United States government,” Romney said in the statement. “Given that kind of threat, we have to adjust our homeland security strategies to confront it.”

The MBTA briefly implemented the system two years ago to address possible security threats to the Democratic National Convention.

A MBTA spokesman, Joe Pesaturo, said that the policy was well-received at that time.

“People have said over and over that safety is their primary concern,” he said.

After the 2005 London bombings, New York’s Metropolitan Transportation Authority instituted a policy of random bag searches based on the MBTA program.

The American Civil Liberties Union (ACLU) challenged New York’s policy in court on the basis that it violated the Fourth Amendment. In August, a federal appeals court upheld a lower court’s ruling that the searches were constitutional—a decision Romney cited in his announcement of the MBTA policy.

John Reinstein, legal director at the ACLU of Massachusetts, said that it is unclear whether the ACLU will challenge Romney’s program.

Although Massachusetts’ policy may be less intrusive than New York’s, the ACLU is still concerned about possible violations of civil liberties, Reinstein said.

“When you set up a screening system that is intended to be used for public mass transit, as opposed to airlines, you are no longer using something that is truly voluntary,” he said. “Most people are going to have to give up some degree of liberty to ride on the T.”

An employee at Gino’s Hair Salon in Harvard Square, Mona Horani, who uses the T to commute to work, said that she considers the policy to be a violation of civil liberties.

“I could see it if there were a terrorist alert, but I definitely don’t think they should be creating it if it’s not necessary,” Horani said.

But some other commuters said they appreciate the increased security efforts.

“People fuss about the increased security on the airlines but they’re glad to have it and they deal with it,” said Jim Hoeper as he emerged from the Harvard Square T stop.

Director of the National Security Program at the Kennedy School of Government Tad J. Oelstrom questioned whether the measure would accomplish its terrorism-prevention goals.

“I don’t know that it’s that effective when it comes to the chance that [MBTA officials] might interrupt that one potential act of terrorist activity,” Oelstrom said.

—Staff writer Stephanie S. Garlow can be reached at sgarlow@fas.harvard.edu.