Jan C. Ting

is a professor of law at the Temple University Beasley School of Law

When Arizona tried to enforce its own standards on illegal immigration, it was told that the issue is exclusively a federal matter. Philadelphia seems to think otherwise.

State and local law enforcement have traditionally tried to cooperate with their federal counterparts. In maintaining good relations, they hope federal agencies will help when backup is needed.

That's how it traditionally works with immigration. When federal Immigration and Customs Enforcement (ICE) learns that a state or local agency is holding someone whose fingerprints and identity match a person it is seeking to deport, ICE issues a detainer request. That request means a person can be held up to 48 hours until ICE can confirm the information and take custody.

On April 16, Mayor Nutter issued an executive order directing city officials to refuse to honor ICE detainers unless all of four conditions are satisfied:

The individual must have been convicted of a crime. Not charged with a crime, however serious, but convicted of a crime.

The criminal conviction must be for a felony.

The felony must involve violence.

Most important, there must be an outstanding judicial warrant for the detention.

In his order, Nutter cites other jurisdictions that have refused to honor ICE detainers. But no other jurisdiction has adopted a policy as rigid as Philadelphia's, with such limited cooperation with the federal agency charged with immigration law enforcement.

ICE is authorized by law to arrest and detain aliens it believes to be removable without a judicial warrant. As the immigration advocates who pushed Nutter to issue his executive order know and have publicly stated, the requirement of a judicial warrant, if it means what it says, will "in practice . . . end all deportation holds" because ICE does not obtain judicial warrants to accompany detainers. The advocates call Nutter's order the "most progressive policy in the country."

What will happen to removable aliens, many of whom have no right to be in the country, when they encounter city police? Under the mayor's order, they will be released onto the streets of Philadelphia despite any ICE request to hold them for removal from the United States.

It's not as though ICE has been particularly vigorous in trying to enforce U.S. immigration law. Under the Obama administration's policy of "prosecutorial discretion," unlawful presence by itself is insufficient to cause ICE to initiate removal proceedings. As the New York Times reports, "New deportation cases brought by the Obama administration in the nation's immigration courts have been declining steadily since 2009," leading to "a 43 percent drop in the number of deportations through the courts in the last five years."

Even while American workers suffer from prolonged high unemployment, underemployment, and stagnant wages because of surplus labor, the Nutter and Obama administrations compete to signal that increased illegal immigration into U.S. and Philadelphia labor markets will be tolerated and not prosecuted.

Business interests welcome increasing illegal immigration as a means to hold down wages and working conditions for American workers. Both Democratic and Republican lawmakers are responsive to the interests of the richest 1 percent, who fund their campaigns. Does anyone believe our political system is operating in the best interests of working-class Americans and Philadelphians?