By Kristen Johanson

PHILADELPHIA (CBS) — Testimony began Thursday in Philadelphia’s federal lawsuit against Attorney General Jeff Sessions over his decision to withhold money approved by Congress to help police departments fight crime.

As part of his crackdown on sanctuary cities, Sessions argues that the new guidelines aim at protecting cities.

Sessions has ordered cities to allow federal authorities to question inmates on their immigration status, and to give officials two days notice before releasing an undocumented prisoner.

Philadelphia Police Commissioner Richard Ross says, although they have a partnership with federal authorities, his department’s policy is not to ask such questions of a suspect, witness, or victim.

“Immigration enforcement is not the business we are in,” said Ross.

He says every suspect is fingerprinted, photographed, and entered into a system that ICE also can access.

Ross says having immigrants feel they will be protected if they need to report crime is imperative to keeping Philadelphia safe. Withholding this $1.6 million, he says, could have a far-reaching impact.

“For our crime suppression efforts, technology, as well as other programs, like mentoring young kids and the like, it is vital that we get that money,” said Ross.

Sessions has argued the sanctuary policy has made citizens and police on the streets “less safe.”