Clackamas County violated a woman's constitutional rights by agreeing to hold her for federal immigration authorities without probable cause, a local federal judge has ruled.

That decision, issued on Friday by a US Magistrate Judge in Portland, thrilled local immigrant rights advocates and has the Clackamas County Sheriff’s Office scrambling to update its policies.

And US Magistrate Judge Janice Stewart's ruling might have far-reaching implications for suspected undocumented immigrants in Oregon and beyond, potentially changing how Multnomah County and others deal with hold requests from US Immigrations and Customs Enforcement.

“I think we should see the tide shift,” says Corinna Spencer-Sheurich, an attorney with the Northwest Workers’ Justice Project. “Hopefully counties will stop honoring ICE holds.”

Under ICE’s Secure Communities program, immigration officials have for years asked jailers to hold suspected undocumented immigrants 48 hours past the point they’d otherwise be released. The idea is that the two-day window will give federal authorities a chance to detain and deport offenders before they have a chance to run off. (The 48-hour window doesn’t count weekends or holidays, so the holds are sometimes longer than two days.)

The holds are a big deal. Scarcely a week goes by these days without some fresh protest or an announcement of a policy tweak surrounding the program. And local advocacy groups have long opposed the program. The American Civil Liberties Union of Oregon has filed suit arguing there is no legal authority behind the immigration holds.

Multnomah County Sheriff Dan Staton made headlines last year, when he announced he’d limit the types of offenders he’ll keep for ICE officials. That tweak was a nod to protestors, but also aimed at easing jail overcrowding.

But even Staton’s revamped policy seems to run afoul of the latest decision.

The case involves a woman named Maria Miranda-Olivares, who was arrested in March 2012 for violating a restraining order. When she pleaded guilty two weeks later, she was given credit for the time she served and ordered released. But, because ICE officials had asked that Miranda-Olivares be detained, she stayed in the Clackamas County Jail for an additional 19 hours.

She sued, arguing that the Clackamas County Sheriff’s Office violated her Fourth Amendment protection against unreasonable search and seizure and her Fourteenth Amendment right to due process, and falsely imprisoned her, to boot. Magistrate Judge Stewart partly agreed.

Stewart sided with a recent federal appeals court decision that ruled local sheriff’s offices aren’t mandated to hold people on ICE detainers just because the agency asks. Local law enforcement agencies have claimed for years that their hands are tied when it comes to abiding by ICE requests (though more and more are bucking that trend). The appeals court decision put the notion to bed, advocates say

But Stewart's ruling went further. Not only was Clackamas County not required to hold Miranda-Olivares for federal officials, the judge found, but it also actually violated her Fourth Amendment rights by doing so, since the jail had no probable cause—an arrest warrant, for instance—to keep her in custody. All jailers had was a federal agency's request.

"The ICE detainer alone did not demonstrate probable cause to hold Miranda-Olivares," the ruling says. "That custom and practice violated Miranda-Olivares’s Fourth Amendment rights by detaining her without probable cause both after she was eligible for pre-trial release upon posting bail and after her release from state charges."

Scott Ciecko, the attorney who represented Clackamas County, said he couldn't comment on the ruling because there are still matters pending.

"We’re weighing our options for how we’re going to proceed," he said.

Miranda-Olivares was represented by the Oregon Law Center, which offers legal aid to low-income litigants. Next, a court will need to determine whether the woman deserves damages for the rights violation.

Much more significant, though, may be how the ruling affects policies around ICE holds in Oregon and beyond.

"The facts of this case are fairly universal," says David Henretty, the attorney who argued Miranda-Olivares' case.

The Clackamas County Sheriff's Office has already scrapped its old practice around the detainers, Sergeant Nathan Thompson tells the Mercury. Gone are the days when deputies would hold an offender based merely on requests. Now, Clackamas County needs to see an order from a judge or magistrate.

"What we’re saying is we’re not going to hold them on just that detainer alone," Thompson said. "It's something we're working on."

Thompson couldn't say how many ICE holds the office agreed to each year, but attorneys familiar with the case estimated that number is in the hundreds.

The decision would appear to have significance in Portland, too. Even with last year's tweaks, Staton's policy allows for offenders to be held for immigration officials without a judge's formal permission.

A Multnomah County Sheriff's Office spokesman didn't return a call for comment.

Meanwhile, organizations that have opposed ICE detainers are cheering the ruling.

"It’s been our position for a long time that this is a very harmful practice," says Becky Straus, legislative director for the ACLU of Oregon. "What we’re now seeing is courts are saying the same thing. The tide is turning."

"It’s not the end of the road," said Spencer-Scheurich, the attorney at the Northwest Workers' Justice Project, who'd been sending the decision around to advocates today. "But it's a good sign for people who are against them."