SWAT teams were designed to diffuse dangerous hostage situations and respond to mass shootings — but in the Tucson area, more than half of what they do is serve drug-related search warrants.

That shift in duties has come under increasing scrutiny, especially the use of “no-knock warrants” that give masked SWAT team members permission to burst into a home without first knocking and announcing their presence. The warrants, which bypass a long-established constitutional requirement that officers identify themselves before entering a home, are allowed under only two conditions — if a judge determines that knocking could pose a risk to the safety of officers or is likely to give suspects an opportunity to destroy evidence.

The Pima County Sheriff’s Department doesn’t use no-knock warrants at all, but the Tucson Police Department has increased the use of them significantly over the past decade.

From mid-2001 through mid-2004, less than 2 percent of the search warrants TPD’s SWAT team used were no-knock warrants. But from mid-2012 through mid-2013, that number soared to about 75 percent, TPD SWAT incident reports analyzed by the Arizona Daily Star show. SWAT teams serve only a small fraction of the search warrants judges grant each year.

But just because a judge grants TPD permission to rush into a home unannounced, that doesn’t mean its SWAT team will actually do that, said Capt. J.T. Turner, commander of TPD’s specialized response division.

Often, officers will breach the door of a suspect’s house without first knocking and announcing their presence, but then stay outside and yell for the occupants to come out, Turner said. From that point, if officers believe a suspect is destroying evidence they can run in quickly, but if not, they can stay outside and wait, he said.

“The TPD SWAT team is very conservative in our use of unannounced ‘no-knock’ dynamic entries into residences due to the obvious, inherent risks of that type of entry,” he said. “There are cases where this is justified and appropriate, but these are the exception and not the rule.”

The SWAT team is now using more of these “breach and hold” entries than breaking in the door and running inside with weapons ready, he said.

Whether officers break through a door and hold back or break through a door and push inside, both are aggressive techniques that can ramp up already tense situations and increase the chance of a violent confrontation, critics say.

“These are paramilitary raids in people’s homes,” said Kara Dansky, senior counsel for the American Civil Liberties Union’s Center for Justice and the lead author of a recent ACLU report critical of SWAT tactics. “That’s not what policing is supposed to be about.”

THE DANGERS OF NO-KNOCKS

Serving a no-knock warrant comes with an inherent risk.

“You really have to take a critical look at all the pieces of the puzzle and make a determination, and a lot of times it’s a judgement call,” Turner said. “Is it going to be safe for me just to send a couple of detectives up to the door with no support, no ballistic protection and no special tools, or should we err on the side of caution and be more prepared?”

The forceful nature of a no-knock warrant can be safer for everyone, Tosca said. The idea is to overwhelm suspects “so they don’t have the ability to react and get to a weapon or destroy evidence,” he said. “It’s not to scare people. It’s to make it safer for both them and the officers serving the warrant.”

Peter Kraska, a professor at Eastern Kentucky University’s School of Justice Studies who has studied policing practices, said his research doesn’t support that claim.

“When you compare the extreme nature of the approach, it just doesn’t make any sense to say that we’re doing this under the auspices of safety,” Kraska said. “They can provide — I promise you — very little evidence that these are hardened, barricaded-in, drug kingpins that are waiting at the door ready to fire at them.”

Occupants of a house where a no-knock warrant is being served can think their home is being invaded when heavily armed officers arrive in an armored vehicle, sometimes late at night.

And if they pick up a weapon in response, fear can turn to violence, he said.

“Walking up in a private residence with 15 officers and throwing concussion grenades, let’s say at 4 o’clock in the morning when people are in the middle of rapid-eye-movement sleep, is incredibly dangerous,” Kraska said.

There are other dangers, too. In May, a 19-month-old Georgia toddler was seriously injured by a flashbang device, which produces noise, smoke and heat, and creates a bright light intended to disorient and confuse occupants of a home where a no-knock warrant is being served.

SWAT officers threw one of the devices into a house where the boy and his family were staying during a no-knock drug raid. It landed in his crib and exploded in his face. The toddler, Bounkham Phonesavanh, was hospitalized for five weeks. SWAT officers were looking for the boy’s cousin, Wanis Thonetheva, a suspected meth dealer who they believed was armed. Thonetheva wasn’t home at the time.

When he was found and arrested later that morning, he had an ounce of meth, but wasn’t armed.

The Pima County Sheriff’s Department SWAT team has cut back on using flashbang devices because they are so disorienting, both to officers and to the public, Pima County Sheriff’s Department SWAT chief Christopher M. Radtke said.

TPD uses flashbang devices on about half the no-knock warrants they serve.

An on-site commander might choose to use one to distract and disorient a house’s occupants and give officers a safety advantage, Turner said.

Tucson police officers refrain from using the devices when they know children are present, former TPD SWAT commander Lt. Paul Tosca said.

“If it’s possible, we would rather call everybody out to us instead of using distraction devices like sometimes we do,” Tosca said. “We don’t want to have that surprise as much, where the children could be traumatized.”

SOME AGENCIES SHUN use

No-knock tactics are mostly used for narcotics-related search warrants because drugs can be quickly flushed down a toilet and those involved in drug trafficking are sometimes heavily armed.

Other factors go into deciding whether to use a no-knock warrant: whether a suspect has a history of substance abuse or emotional instability, or lives in a house that is heavily fortified or equipped with counter-surveillance that would let residents see police approaching.

But even if those conditions are met, some agencies shy away from no-knock tactics. When Pima County Sheriff’s deputies serve a search warrant, they knock and announce their presence, or surround the house and wait for the occupants to come outside.

“I’ve been doing this for 38 years, and I have never, ever seen or done a no-knock warrant,” Chief Deputy Chris Nanos said.

He doesn’t criticize TPD for using the tactic. It’s a tool the sheriff’s department doesn’t want to exclude, he said.

Still, sheriff’s officials feel avoiding no-knock warrants is safer both for their officers and for the public.

“Your intel is not always correct that there are not infants, that there are not children in the house,” Radtke said.

Even though the U.S. Supreme Court has given officers permission to use no-knock warrants, “it still doesn’t relieve you of the responsibility to know that one’s home is one’s sanctity,” Nanos said. “Even if we have a warrant, it’s just a matter of constitutional law 101 that says when you get into someone’s home, you are really invading their privacy.”

But even when SWAT teams knock and announce their presence before entering a home, things can go wrong.

In May 2011, the sheriff’s department’s SWAT team shot and killed former Marine Jose Guerena while attempting to serve a drug-related search warrant at his home.

Guerena’s wife has said she woke her husband after she saw a man with a gun outside their window and after the SWAT team deployed a flashbang device. Believing intruders were breaking into their home, Guerena instructed his wife and their 4-year-old son to hide in a closet while he grabbed an AR-15 rifle.

Although the safety was still on Guerena’s weapon, SWAT officers saw the weapon when they entered his home and fired about 70 rounds at him. Medical examiners recovered 22 bullets from his body.

The sheriff’s office has learned from its mistakes, Pima County Sheriff’s Department SWAT Capt. Michael Sacco said. “Every call, every warrant, gets debriefed by the SWAT team and their commander,” he said. “And they are painfully frank and open about what did or didn’t happen.”

But the Guerena case and others like it have led no-knock critics like Kraska to question the justification for using such aggressive tactics to serve drug-related search warrants, whether “knock and announce” or no-knock warrants are used.

“Is this extreme, Navy SEALs approach of policing an intelligent, safe, decent way to police in a democratic society?” Kraska said.

To him and the ACLU’s Dansky, the answer is no. And there’s a lot at stake, they said, in getting that answer right.

“If people aren’t being treated fairly by the police,” Dansky said, “that undermines public trust and, ultimately, public safety.”