Two months after the arrest of two black patrons at a Philadelphia Starbucks caused national outrage, the city's Police Department is instituting a new policy for handling trespassing calls.

In a major change announced Friday by Philadelphia Police Commissioner Richard Ross, officers are now required to attempt "to de-escalate and mediate the disturbance" and to use their discretion with trespassing allegations on private property that's open to the public.

Police officers arrest Rashon Nelson inside a Starbucks cafe in Philadelphia on April 12. Melissa Depino / Reuters

Before making an arrest, the officers are now expected to determine that the offender understands the request to leave the establishment and then witness the person refusing to honor a legitimate request. Officers may also call a specialist trained in crisis intervention or a supervisor to help determine how to proceed.

“It's a step in the right direction. We’re glad that the Police Department is being proactive in addressing the issues that arose with the Starbucks arrest," Sara Rose, a staff attorney for the ACLU of Pennsylvania, told NBC News. "It's a policy that looks pretty good on paper, but there needs to be follow-through — in the training of officers, and holding those officers that don’t comply accountable.

"It's not a panacea."

Philadelphia civil rights attorney David Rudovsky called the new policy "a potentially significant change."

Rudovsky said that of particular importance is the new policy's ties with Philadelphia’s Fair Practices Ordinance, which protects individuals against unlawful discrimination by businesses.

The policy change comes two months after the April 12 arrest of Donte Robinson and Rashon Nelson, who were told to leave a downtown Philadelphia Starbucks store — despite their protests that they were customers waiting on a business contact before ordering.

As national outrage mounted after a video of the arrest taken by another customer went viral, Ross at first publicly defended his officers' handling of the arrest of the 23-year-old businessmen. But a subsequent policy review found that there was no procedure and little room for nuance in the enforcement of Pennsylvania's state criminal code for trespassing.

Last month, the city settled with the two men, declining to prosecute, expunging their arrest record and creating a $200,000 fund to assist young entrepreneurs in Philadelphia. Ross promised substantive changes to police policy at the time, and on Friday seemed to make good on that vow.

"The new policy provides officers with guidance on how to respond to calls about trespassing on private business properties that are open to the public," Ross said in a statement Friday. "This allows police to take actions, with the help of their supervisor, that are most appropriate in each individual case.”

Rudovsky added that the police need to combine the new policy with an outreach effort involving business owners in their individual districts.

"There needs to be conversations between captains and store owners to both advise them of this policy and underline the fact that the Police Department has concerns whether some of these trespassing calls are reflecting racial bias," said Rudovsky.

The arrest of Nelson and Robinson had far-reaching effects on the national conversation about racism well outside the city limits of Philadelphia. Starbucks closed all 8,000 of its U.S. stores for an afternoon on May 29 to provide bias training for its employees. The coffee chain also announced a change of policy to allow anyone to sit in one of its stores or use its restrooms without purchasing anything.

All that national media attention had a profound effect back in Philadelphia.

"There were definitely steps taken by the Police Department today that would definitely not been taken if not for what happened in that Starbucks branch," said Rose.