A federal judge in Alabama has temporarily blocked a controversial state law that is designed to sharply curtail illegal immigration in the state.

The ruling was released early Monday afternoon, three days before the law, considered one of the most expansive in the United States, was scheduled to go into effect.

Judge Sharon L. Blackburn said the courts need at least a month “to adequately address the numerous challenges” to the law and that the injunction will remain in effect until Sept. 29, “or until the court enters its ruling, whichever comes first.”

Judge Blackburn indicated that at this stage her ruling should not be interpreted as a critique of the law. “In entering this order the court specifically notes that it is in no way addressing the merits of the motions,” she wrote.

The order follows a nine-hour hearing last Wednesday in federal court in Birmingham that pit special interest groups and US Justice Department attorneys against state legislators who sponsored the bill, which was signed into law June 9 by Gov. Robert Bentley.

Governor Bentley, a Republican, told the Montgomery Advertiser Monday he was “not surprised by the delay” and that he remains assured that “this bill is a good bill.”

“It was well written. It mirrors federal law, and I expect that it will be upheld,” he said.

Republican legislators in the state complimented Blackburn’s decision to deliberate further and said they were confident her final ruling will be in their favor. In the hearing they made the argument that states had a right to govern illegal immigration because the federal government was not doing enough to enforce its own laws.

“We must remember that today’s ruling is simply the first round in what promises to be a long judicial fight over Alabama’s right to protect its borders,” said the House majority leader, Micky Hammon, in a statement.

Similarly, House Speaker Mike Hubbard and Senate President Del Marsh said in a joint statement they were “encouraged” by Blackburn’s order as it suggested “her willingness to carefully examine all aspects of the case prior to the ruling.”

The 72-page law, formally titled the Beason-Hammon Alabama Taxpayer and Citizen Protection Act, is a detailed breakdown of how Alabama wants to prevent illegal immigration in its state.

The law deprives illegal immigrants of most local public benefits and makes it a crime for them to seek work in the state. In addition, those who knowingly employ, harbor, or transport people they know are illegal immigrants face felony charges.

The law also requires the state’s public elementary and secondary schools to determine that each child enrolled in its classrooms as well as their parents are legal residents.

Alabama residents would also be required to show proof of their legal status when applying for or renewing a vehicle license plate, and when applying for a business or driver’s license.

During the hearings, Blackburn said she was concerned that much of the language in the law was unclear and that she found “a lot of problems” with some of its procedural aspects.

On Sunday, several hundred people rallied in the streets of Montgomery, the state capital. According to the Montgomery Advertiser, two Democratic state senators, Hank Sanders and Quinton Ross, attended the rally.

Senator Ross told the crowd he was “ashamed” of the law and that even though his party is “in the minority,” they “will continue to fight on behalf of all Alabamians.”