ATLANTA - Civil liberties groups argued Monday that Georgia's law cracking down on illegal immigration should not take effect until a lawsuit challenging it as unconstitutional is resolved, and a judge said he likely would rule on that request before the law takes effect.

The lawsuit asks a judge to find the law unconstitutional and to prevent its enforcement. U.S. District Judge Thomas Thrash also heard arguments from a lawyer for the state, who said the lawsuit should be dismissed. Thrash repeatedly questioned Senior Assistant Attorney General Devon Orland, with the exchange sometimes bordering on testy.

Omar Jadwat with the American Civil Liberties Union argued the law is fundamentally unconstitutional and infringes on federal authority, while Orland said the measure is needed because medical facilities and prisons are being strained by illegal immigrants.

The possible harm the law could inflict on people and organizations is greater than any harm done to the state without the law, so it should be blocked until the courts rule on the merits of the legal challenge, said Karen Tumlin from the National Immigration Law Center.

At the end of the hearing, Thrash said he needs more time to consider the arguments because the legal and constitutional issues at play are complex. He expects to decide on the issue before July 1, when most parts of the law take effect.

"We're optimistic," Jadwat said after the hearing. "The judge seemed to grasp a lot of the practical problems posed by this law."

The attorney general's office said it's waiting for the judge's ruling and declined to comment.

The measure authorizes law enforcement officers to check the immigration status of suspects who cannot provide identification and to detain and hand over to federal authorities anyone found to be in the country illegally. It also penalizes people who, while committing another crime, knowingly transport or harbor illegal immigrants and makes it a felony to present false documents or information when applying for a job.

During the hearing, Thrash on more than one occasion told Orland not to interrupt him and said she wasn't answering his questions.

The judge expressed concern that the new law allows individual jurisdictions too much discretion, effectively creating a different policy in every county. He also questioned the motive behind the law. Orland responded that it was to prevent the state from continuing to spend money on illegal immigrants.

"So they're supposed to go somewhere else with their husbands, their wives, their children, even though some of them may be U.S. citizens?" Thrash asked.

Thrash later questioned provisions dealing with people who harbor or transport illegal immigrants, raising a hypothetical scenario of an 18-year-old U.S. citizen who gets pulled over for speeding while driving his mother, an illegal immigrant, to the store.

"It would be no different if his mother had pockets full of cocaine and he was knowingly transporting her to go sell it," Orland said, later adding: "Sometimes the law is harsh. There is no question about that. That does not make it unconstitutional."

Orland also said that other parts of the law would actually protect illegal immigrants from exploitation, and that parts of the state policy mirror federal immigration law.

Jadwat argued that the state isn't mirroring federal law because the Georgia law gives local officers such broad enforcement discretion, and that the state is not authorized to enforce certain parts of federal law.

Georgia's law has provisions similar to those in laws enacted in Arizona, Utah and Indiana.

A federal judge blocked the most controversial parts of Arizona's law last year after the U.S. Department of Justice sued, arguing that only the federal government can regulate immigration. A federal appeals court judge upheld the decision, and Arizona Gov. Jan Brewer has said she plans to appeal to the U.S. Supreme Court.

A federal judge also has temporarily blocked Utah's law, citing similarities to the most controversial parts of Arizona's law. A hearing is set for mid-July to determine if the law can take effect. And in Indiana, a federal judge is set to hear arguments Monday over whether that state's law can take effect next month.

Another section of the Georgia law set to be phased in starting in January will require many businesses to check the immigration status of new hires. A separate Arizona law with the same requirement was recently upheld by the U.S. Supreme Court.