Police departments across the country are implementing extra safety precautions after gunmen killed eight officers and wounded 10 others in Dallas and Baton Rouge, La., in the past two weeks. In many cities -- including Baltimore, Boston, Chicago, Cleveland, Denver, Milwaukee, New Orleans, New York and Washington, D.C. -- police chiefs have ordered their officers not to patrol alone for the foreseeable future.

For so many departments to adopt the tactic is unusual, said Darrel Stephens, executive director of Major Cities Chiefs Association, “but to have direct attacks on police, two of them back-to-back, is a pretty unusual situation. I think people can understand that police might be concerned about their safety.”

Some, however, worry that the new policy may slow response times, force officers to work even more overtime than they already do and strain tight law enforcement budgets. According to the Associated Press, "response times could slow for lower-priority cases, like thefts, that typically require just one officer."

Having police travel in pairs is intended to deter confrontation and violence in the first place. A person might have second thoughts about resisting arrest or running away if they're outnumbered. If there is an attack on police, having an extra officer could help stop the shooter.

But in Dallas, where a sniper shot officers from an elevated position, experts say two-person patrols wouldn’t have made a difference. In Baton Rouge, where the shooter was on the ground, “it’s open to speculation,” said Stephens.

According to Milwaukee Police Chief Ed Flynn, "research and experience have overwhelmingly demonstrated that officers are not made any safer in a two-officer squad." But he decided to make them a requirement right now anyway “out of an abundance of caution and in recognition of expressed concerns.”

In Cleveland, another city to adopt two-person patrols, officers also have to worry about being at higher risk because of the Republican National Convention this week. To increase security during the event, the city is recruiting additional manpower from neighboring cities and counties.

The law enforcement community has debated the effectiveness of two-officer patrols for decades. The primary evidence against the practice is a 1977 study that found one-person patrols were just as safe, cheaper and made more arrests. Critics of two-person patrols also argue that officers can cover more area by themselves and call for backup when necessary.

But Stephens argues that it makes sense as a temporary measure after the two recent attacks on police.

“One study almost 40 years ago shouldn’t guide policy today,” said Stephens. “Whether there’s any evidence at all, I think it does in fact make police officers more comfortable on the street under some trying circumstances.”