Phoenix ? Unless it is halted by a judge, Arizona’s new immigration law is set to take effect July 29.

The Justice Department and civil rights groups have filed suit against the law, arguing that immigration is the purview of the federal government and that SB 1070 will promote racial profiling.

Q. What does the law do?

A. The law essentially mandates that local governments in Arizona enforce immigration laws. The provision that has received the most attention is the creation of a new state crime: failure to possess proper immigration documents.

SB 1070 also forbids local entities, such as city councils or police departments, from making it a policy to ignore federal immigration laws. It allows people to sue if such a policy is formulated.

However, it may take months or years to learn the impact of the law because judges will likely rule on how it can be implemented.

Q: What are police required to do under the law?

A: If officers stop, detain or arrest people while enforcing other laws or ordinances and reasonably suspect they are in the country illegally, they have to try to determine their status if it’s practicable.

In other words, police don’t have to determine someone’s legal status if there’s a shootout going on. They also get a pass if inquiring would hinder an investigation — by scaring off witnesses, for example.

Q: How does this change things?

A: Currently, all law enforcement officers in the country, unless forbidden by management, are allowed to check on the immigration status of people they stop or arrest. This makes checking a requirement.

Police departments generally notify federal immigration officials when violent criminals who are illegal immigrants are being released from jail. SB 1070 makes it mandatory, and applies to low-grade offenders as well as violent felons.