By Jude Joffe-Block, Fronteras Desk

PHOENIX — The U.S. Supreme Court's decision to allow part of Arizona's immigration law to go forward means police in the state will soon be required to check immigration status if they suspect illegal presence.

That is, unless plaintiffs in a parallel lawsuit block that from happening this week.

The high court's decision that Section 2B of SB 1070, also known as the "stop and check" provision, can go into effect, means the preliminary injunction blocking that provision will be lifted by lower courts sometime after Friday.

Before that date, a coalition of civil rights advocates litigating a separate federal lawsuit challenging SB 1070, could ask the judge in their own case to block Section 2B from going into effect. If they choose that strategy, their request would be based on different legal grounds than the Supreme Court examined.

"Our case raises Fourth Amendment arguments dealing with unlawful detention and the possibility that people are detained for long periods of time simply because of their immigration status," said Alessandra Soler, executive director of the ACLU of Arizona.

In contrast, the federal government argued before the Supreme Court that the provision should be blocked because it is preempted by federal law.

Still, the coalition of civil rights groups will not necessarily try to block Section 2B of the law from going forward. Instead they could wait for it to take effect and then challenge it based on how it is being used in practice.

"So our attorneys are weighing both options right now," Soler said.

Fronteras Desk is a collaborative project of public media entities in Arizona, California, Nevada, New Mexico and Texas, including Arizona Public Media.