The judges of the U.S. Court of Appeals split straight down liberal and conservative lines last week in a classic skirmish over a rule of criminal law that has provoked emotional debate since it was first raised by the U.S. Supreme Court 67 years ago.

The issue is the so-called "exclusionary rule," which blocks prosecutors from using evidence in criminal trials that was obtained by police during illegal searches.

The civil libertarians say the rule keeps police conduct in line with constitional protections against unreasonable searches and seizures. But law and order conservatives complain the rule (which comes up most often in narcotics and weapons cases) unnecessarily impedes the war on crime.

The case involved Albert (Bandit) Ross Jr. who was stopped by police in 1978 on an informant's tip that he was selling drugs out of the trunk of his maroon Chevy Malibu. In the trunk, the officers found a folded brown paper bag and a zippered red leather pouch. Without a search warrant, the police opened the bag and found 30 glassine envelopes of heroin. Ross was hauled off to the police station where the police looked in the red leather pouch (also without a warrant) and found $3,200.

Last week, the full court of appeals, in a 7-to-4 vote, said that the police were wrong when they searched the bag and the pouch without a warrant.

Led by Circuit Judge Ruth Bader Ginsburg, the freshman member of the court and the author of lined up one after another in the majority -- Judges J. Skelly Wright, Spottswood W. Robinson, Patricia M. Wald, Abner J. Mikva and Harry T. Edwards along with Chief Judge Carl McGowan, the court's swing man.

Things were not so neat on the dissenting side.

A year ago, in a decision promptly vacated by the full court, a three-judge appeals panel had said okay to the bag search but not to the pouch. The difference (according to Circuit Judge Edward A. Tamm, who wrote the majority opinion then) was that an expectation of privacy, protected by the Constitution, is attached to things like luggage (such a zippered pouches) but not to flimsy things like paper bags. Therefore, the police did not need a warrant to look inside the bag but they did need one to look inside the pouch.

Tamm was joined in his opinion by U.S. District Judge Harold H. Greene (sitting in the appeals court by special designation), a liberal jurist who seemed in an unlikely alliance with the traditionally conservative Tamm. Senior Judge David L. Bazelon wrote a blistering 17-page dissent in which he accused Tamm and Greene of "accute ethenocentric myopia" for demeaning people who carry their belongings in a paper bag instead of an American Tourister.

The majority of the court agreed with Bazelon last week and said paper bags were as good as pouches when it came to constitutional protections against warrantless searches.

Ross was represented on appeal by a court-appointed lawyer, William J. Garber, who is said to be the brains behind flamboyant defense lawyer Kenneth Michael Robinson.

A brief for Ross was also filed by Michael Geltener and Larry J. Ritchie for the Georgetown Law Center Appellate Litigation Clinic. The clinic has bad its share of big victories in the appeals court this year, including the reversal of a 17-year-old murder conviction and an order for new trials for the men charged with the assasination of former Chilean ambassador Orlando Letelier.

The Ross case became somewhat of a cause celebre at the federal courthouse where provative criminal law questions have been scarce since the early 1970s when the bulk of criminal cases were taken over by the D.C. Superior Court. Overflow crowds showed up to hear oral argument before the full appeals court last October. The Village Voice even ran an irreverent column about the case, predictably lauding the Bazelon brown bag dissent.

But since Bazelon is a senior judge and Greene is a district judge, neither was included in the full court's reconsideration of the case. That left Tamm from the original three-judge panel. He stuck to his earliler holding that the paper bag search was legal. Judge Roger Robb concurred. All four dissenters wrote separate opinions.

As far as Judge George MacKinnon was concerned, the pouch didn't qualify as a piece of luggage anymore than the paper bag and therefore none of the legal cases involving searches of luggage applied in the Ross dilemma. MacKinnon said in his dissent that there was enough probable cause to support stopping Ross' car and seizing the bag and the pouch and said "the police would have acted unreasonably in my opinion if they had not merely looked inside."

MacKinnon also cited some support for his argument from an episode in the comic strip "Andy Capp," in which Capp made fun of his wife's mother who ambled off to the bus station with her "matchin luggage" -- two supermarket bags.

Circuit Judge Robb, also in a one-page dissenting opinion, said he felt he was compelled by Supreme Court decisions to agree with Tamm on the pouch question, but he said he thought that the right to search a car ought to include the right to open any containers found inside.

The legal test for a warrantless search of a container is whether the owner had a reasonable expectation that its contents would be kept private. But, Robb said that standard only causes doubt and confusion for the police and the courts.

It was Circuit Judge Malcolm Richard Wilkey, in what was plainly an invitation to the Supreme Court to change the law, who used his 63-page dissent in Ross to call for abolition of the exclusionary rule. When the police blunder, Wilkey says, citizens should be able to seek compensation for illegal searches in the federal courts under the civil rights laws.

In a final footnote, Wilkey says he'd actually prefer Congress to dispose of the rule and not the courts. But he notes that Chief Justice Warren E. Burger's call for such legislation in his dissent in a 1971 exclusionary rule case met with a silence that has been "thundering."