Scenarios: What could happen with Arizona's immigration law

WASHINGTON (Reuters) - A U.S. judge in Arizona has put key parts of the border state's tough new immigration law on hold before it is due to come into effect on Thursday.

The U.S. Justice Department had argued provisions of the law encroached on federal authority over immigration policy and enforcement.

Here are some scenarios for what could happen next:

ARIZONA PLANS TO APPEAL

Arizona's Republican Governor Jan Brewer said the state plans to file an expedited appeal with the U.S. Court of Appeals for the Ninth Circuit seeking to lift the injunction against the immigration law.

The appeals court, based in San Francisco, could consider whether to lift the injunction and let the full law go into effect or request legal briefs and arguments from both sides before ruling on Arizona's request.

It was not clear how quickly Arizona would move to file its appeal. Regardless of how the appeals court rules, either side could then appeal that decision to the U.S. Supreme Court.

U.S. COURT HEARS FORMAL ARGUMENTS

While Judge Susan Bolton granted a preliminary injunction against the Arizona law, she did so on the grounds that she believes the Obama administration would ultimately succeed on the merits of the case when presented in court.

Therefore, Bolton would still need to hear arguments from both sides on the merits of the federal government's challenge, requiring lengthy legal briefs, and likely hear oral arguments, a process that can take months.

Either side could then appeal to the Ninth Circuit and ultimately the Supreme Court.

CONGRESSIONAL ACTION

With the initial victory in hand, that could lead some lawmakers in the U.S. Congress to try to forge a compromise on a comprehensive immigration reform plan that has been elusive regardless of which political party holds the White House.

But the chances are slim that the Obama administration and lawmakers will reach a deal before November's congressional elections in which Republicans are expected to make gains.

Republicans demand more effort to secure the southern border with Mexico and have said the initial deployment of National Guard troops to the border was inadequate.

Many Republicans also oppose giving amnesty to the nearly 11 million illegal immigrants believed to be in the United States to allow them to remain in the country.

Obama supports allowing undocumented immigrants in good standing to pay a fine, learn English and get on the track to citizenship. He also has supported tightening border security and clamping down on employers that hire undocumented workers.

STATE LEGISLATURE

With the ruling, the Arizona legislature could try to alter the law to address concerns raised by Judge Bolton. Arizona's governor could call a special session to make those changes.

State lawmakers already have amended the immigration law once to try to prevent racial profiling. Under the changes, police will be required to investigate the immigration status of people they reasonably suspect are in the country illegally only in the case of lawful contact such as a traffic stop.

(Additional reporting by Tim Gaynor in Phoenix; Editing by John O'Callaghan and Vicki Allen)