As Oregon heads into another booze-soaked weekend, police agencies and prosecutors are scrambling today to plan how to deal with DUII arrests after what could be a landmark Court of Appeals decision this week.

Prosecutors say the 6-4 ruling filed Wednesday could force changes in the way police handle DUII arrests. A majority of the appeals court ruled the officer should have obtained a warrant and that the suspect was coerced into giving a blood sample.

"We potentially lost the blood alcohol content in every single open DUI (case), which is huge," says Adam Gibbs, a Multnomah County deputy district attorney.

Gibbs' office held a meeting late Friday afternoon to hatch an emergency plan for how police should deal with DUII stops until there's clarification on the court's ruling. Some counties have already advised their police to obtain a warrant for every DUII stop until further notice.

The court case dates back to June 1, 2005. That's when Gregory Machuca of West Linn crashed in a single-car accident on Naito Parkway in Portland. He was taken to the emergency room at Oregon Health & Science University, where Portland Police Officer Joshua Ladd arrived at 1:52 a.m. to investigate.

According to the court's written ruling, Machuca — a bar manager who was 37 at the time of the crash — consented to Ladd's request at the hospital to take a blood test for alcohol. Based on the results (which were not in the court's written ruling), he was charged with reckless driving and DUII.

The reckless driving charge was later dismissed. Machuca entered a conditional guilty plea to DUII and was sentenced in 2006 to four days in jail, a one-year license suspension, three years of probation and a $1,000 fine.

But the six-judge majority overturned Machuca's conviction this week, ruling that the blood test, obtained under so-called "implied consent" by Machuca, should not have been allowed as evidence.

The reason: The majority ruled that Machuca's consent was actually coerced from him, because like other DUII suspects, he faced a $1,000 fine and a one-year license suspension if he refused to take the test.

Because coercion was used, the majority ruled that implied consent doesn't apply and the blood test must be thrown out.

The only time cops can bypass implied consent is when there's probable cause for a crime and they can prove "exigent circumstances" — i.e., that evidence will be lost if they don't get it immediately. The majority ruled that exigent circumstances didn't exist in this case, saying Ladd had plenty of time to obtain a warrant.

Since most DUII arrests rely on implied consent to obtain a breath test, the case could deal a major blow to the way cops operate.

Prosecutors will no doubt appeal the decision to the state Supreme Court. But for now, defense attorneys are ecstatic about the ruling.

"It reaffirms things that I have been arguing and saying for decades about the necessity to keep your eye on the Constitution, even when it's a DUII case," says John Henry Hingson III, a top DUII defense lawyer.

The majority included judges David Brewer, Walt Edmonds, William Riggs, Darleen Ortega, Timothy Sercombe and Ellen Rosenblum (full disclosure: Rosenblum is married to WW Publisher Richard Meeker).

The dissenting judges were Rick Haselton, Jack Landau, Rex Armstrong and David Schuman.

In a footnote to the case, Machuca was arrested again less than two weeks ago — on Sept. 19 — and charged with DUII, reckless driving and recklessly endangering another person. He has pleaded not guilty to all charges.