She said the office might request that kind of information in the future. In the meantime, the governor and his staff continue to review the statistics, looking for significant changes that would require further examination, she said. So far, the figures have been steady.

Still, critics point to examples such as a 2009 raid in Howard County, when the resident of an Elkridge mobile home said officers hit him in the face with a shield, knocking him to the ground, and shot one of the family dogs.

Police were searching for a high-powered rifle and nearly 150 rounds of ammunition that had been stolen from police cruisers in a nearby neighborhood. Police said an informant told them that the stepson of the mobile-home resident might have been trying to sell an assault rifle, but they did not find the rifle or ammunition.

In the July raid in Reisterstown, police wanted to serve a search warrant in an attempted-murder case, and the suspects were facing concealed-weapons charges.

"Police officers are alive because of [the tactical unit's] existence and how well trained they are," said Cole B. Weston, president of the Baltimore County Fraternal Order of Police. "If you did not have them, or their expertise, you would lose more police officers."

But critics, including Calvo, said that while some cases might warrant tactical deployments, the raids are too frequent.

"These quasi-military tactics used by police departments are unnecessary in most investigations," said Brian G. Thompson, a Baltimore County defense attorney who has represented clients whose homes have been raided.

Fatalities and injuries are inevitable when such tactics are used because "people don't know what was happening," Thompson said. Even when police have identified themselves, residents are startled awake and a natural reaction is to reach for a gun, he said.

"There's certainly a place for these tactics, but more often then not, [police] can conduct surveillance" instead, he said.

Tim Lynch, director of the Cato Institute's Project on Criminal Justice, agreed, saying there has been an alarming increase in the use of tactical units across the nation.

"It's gone from an exceptional set of circumstances to routine police calls," he said, listing deployments around the country for matters ranging from graffiti to child pornography.

Police, he said, "need to do the investigations," which might reduce mistakes such as identifying the wrong address. He said that in many instances, officers could wait until the suspects walk outside to avoid endangering innocent people inside.

He applauded Maryland's effort to track how often and why tactical units are used.

"Law enforcement around the United States are heavily decentralized. There are no statewide rules governing use" of tactical deployments, he said. "That's why that reform has kind of stood out."

He added, however, that "much more needs to be done here about when police raid our homes. The great American principle is that our homes are our castles."

Calvo said the next step is for the state to conduct more in-depth analysis of the data on raids. He says that looking at data on a calendar-year basis, which the state does not compile, deployments have risen 13 percent, from 1,526 deployments in 2010 to 1,722 in 2011.

He'd like to see legislators create a task force to evaluate the findings, potentially adopting a best-practice standard for departments to follow when deploying tactical units.

He's concerned about the number of deployments used in nonviolent cases such as drug investigations.

"You have to have data to give you a sense of what's going on here," Calvo said. "You need to have policies in place when police are taking action that people can monitor."

Baltimore Sun reporter Tricia Bishop contributed to this article.

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