Among other changes, the commissioner ordered that suspects who have not been charged with a crime may not be held in police custody for more than 36 hours. He also directed that witnesses be reminded that they may leave at any time.
Finally, Ramsey imposed new rules on how police display mug shots to witnesses in an effort to ensure more accurate results.
The new measures were more than a year in the making, the commissioner said, the result of several meetings among department brass, civil rights lawyers, and representatives from the Pennsylvania Innocence Project.
Civil rights lawyers David Rudovsky and Dennis J. Cogan approached the department last year with a list of a half-dozen witnesses in criminal cases who complained that they had been held in police custody for long hours or threatened with arrest before they gave statements.
"We sat down and we hammered it out," Ramsey said. "It's positive, and I'd like to see more of it."
The new policies were first reported by the Philadelphia Daily News.
Beginning Jan. 1, interrogations of homicide suspects will be video-recorded, the commissioner said, and eventually, all detective divisions and the Special Victims Unit will be required to record interrogations as well.
That's a policy Ramsey instituted as police chief in Washington - and one that sparked some controversy among the rank and file.
But, he said, the video recordings can prove useful in court.
"This is something that strengthens cases, not weakens them," he said.
Lt. Philip Riehl of the Homicide Unit called the directive "a new hurdle" that "everybody will adapt to."
"Will this policy impact the performance? I don't think it will. I think that guys are going to work even harder to try to accomplish the same goals," he said.
Homicide interrogations have a long and fraught history in the city.
In 1977, The Inquirer reported that Philadelphia homicide detectives often beat suspects and witnesses in murder investigations, then lied about it under oath. The paper reported that as many as 17 percent of all confessions had been obtained illegally in the years before it published its findings.
As a result of the newspaper's stories, the U.S. attorney and the FBI launched a civil-rights investigation of homicide interrogation methods, as well as incidents of police violence on the streets.
Ultimately, federal prosecutors convicted six detectives of conspiring to violate the civil rights of a mentally challenged man, Robert "Reds" Wilkinson, who had falsely confessed after beatings that he had tossed a firebomb that killed five people.
While critics have not alleged a return of that kind of systemic problem, interrogations have still come under criticism.
In 2011, prosecutors dropped murder charges against a West Philadelphia woman, Unique Drayton, after a judge suppressed the use of the confession she gave to police after being held for 41 hours.
"The statement that she made was not voluntarily made, but was the product of psychological coercion," Common Pleas Judge M. Teresa Sarmina said at the time.
Ramsey called such incidents isolated.
He said he would reiterate to detectives that they must tell witnesses that they may leave at any time. That is the department's current policy, but Ramsey said, he will now put it in writing.
In the past, witnesses have complained that they were kept at Police Headquarters for hours.
Brittany Johnson, 25, said she was hauled out of her home in handcuffs last year, while her 5-year-old son watched, when police wanted to talk to her about her boyfriend, a suspect in several home-invasion robberies.
In an interview Thursday, Johnson said she was held for about 30 hours in a locked room when investigators doubted her contention that her boyfriend kept his street activities to himself.
"Until you cooperate, you're not leaving," she said police told her.
She said they rebuffed her pleas to leave, her request for a lawyer - even a request for water.
At one point, she said, a detective snatched a cup of water out of her hand just as she was preparing to take a sip.
"You're not going to get to drink until you cooperate," she said the detective told her.
In another change Ramsey has ordered, the department will alter how it presents mug shots to witnesses and victims.
In the past, police would show witnesses a book of photos or ask them to survey six to seven photos looking for a potential suspect.
Now, Ramsey said, a detective not involved in the case will show a witness photos of potential suspects one by one. Ramsey said that method has proven more accurate in identifying suspects.
Civil rights lawyers said they were pleased that Ramsey had welcomed their input.
"If we think there's a problem, we approach the department first," Rudovsky said. "We think it's important enough that we can litigate, but it's been our practice to try to resolve stuff amicably first."
Marissa Bluestine, legal director of the Pennsylvania Innocence Project, said the new measures could set an example across the state.
"A lot of chiefs across the state look to [Ramsey] and say, 'OK, they're doing it in Philly - maybe we can do it in Pittsburgh, or York, or Erie," she said. "We believe that Philadelphia will be the big domino to fall."