The U.S. Supreme Court declined Monday to review a Frederick County case in which a woman challenged local authorities' power to arrest her on an immigration violation, cementing her victory in a case that has been closely watched by both sides of the immigration debate.

Supporters of Roxana Santos, a Salvadoran immigrant, said the decision shows that Frederick County overstepped the law with its aggressive stance on immigration enforcement.

Santos said she was arrested after being approached by Frederick County sheriff's deputies while she was eating lunch in October 2008. She sued the county and Sheriff Chuck Jenkins after 45 days in jail, alleging that the officers violated her Fourth Amendment rights against illegal search and seizure. She also accused the county of profiling her.

"It's an extremely significant decision in that it makes clear that local law enforcement should stay out of immigration affairs," said Sirine Shebaya, an attorney for the American Civil Liberties Union of Maryland. "It draws a really bright line."

But county officials who support the tough approach say the lower court's decision backing Santos has limited the enforcement powers of its officers.

Frederick County Commission Vice President C. Paul Smith said the ruling was "better for those who are doing something strange and breaking the law" than for police. The county alleged that Santos tried to hide from the deputies, which drew their suspicion.

A lower court dismissed her suit, but Santos appealed last August to the 4th U.S. Circuit Court of Appeals and won.

She seeks $1 million in damages but would drop the case if the sheriff's department revises its policies, according to Jose Perez, deputy general counsel of LatinoJustice, one of the groups representing Santos.

The case has played out as Congressional action on immigration reform has stalled. Courts around the country, meanwhile, have come to different conclusions as they seek to balance individual rights with enforcement efforts.

A law making its way through the state legislature may force the county's hand. Dubbed the Maryland Enforcement Trust Act, the law would make clear local and state officials cannot detain people nor deny bail solely because of immigration-related infractions. The bill is up for a committee vote this week.

The Frederick County Sheriff's Office did not respond to requests for comment Monday.

After Jenkins was elected, Frederick County signed onto a federal program that allows local law enforcement to research immigration information. It was the only jurisdiction in the state to do so, and hundreds of people in the country illegally have been deported from there since 2008.

Blaine R. Young, the president of the Frederick County board of commissioners, said the policy "puts law-abiding citizens first" and is often misinterpreted.

He added that immigration is a hot-button issue, but that the discussion should center on whether police can arrest people on civil warrants.

"We need to separate the immigration issue from it," he said.

Smith said he wants police to be vigilant when they see suspicious behavior.

"If something looks strange, you like them to look into it," he said. "She sees the police and runs away. Golly, how are you going to articulate that standard of what constitutes illegal?"

The ACLU's Shebaya said the case has made the issue more clear-cut: "If there's not a suspicion of criminal activity, don't stop the person."

Shebaya compared the case to a 2012 Supreme Court ruling that Arizona could not require immigrants to carry documentation and police could not arrest people they suspected were in the country illegally.

Ira Mehlman, spokesman for the Federation for American Immigration Reform, which advocates for tougher immigration enforcement, said the Frederick County case should have been heard because the federal circuit courts have delivered uneven rulings on how local jurisdictions should enforce immigration.