BANGOR – A Canadian man whose case may be headed to the U.S. Supreme Court pleaded guilty on Friday in U.S. District Court to marijuana smuggling.

Joshua D. Gabriel, 29, of Ontario entered his plea on the condition that he can appeal the stop that led to his arrest to the 1st Circuit Court of Appeals in Boston and, if necessary, to the U.S. Supreme Court.

A sentencing date has not been set.

He is facing up to 20 years in prison and a fine of up to $1 million and could be forbidden from entering the United States again. Gabriel also has agreed to forfeit the $4,060 in cash found in his minivan and the $7,000 Rolex watch he was wearing.

Gabriel was arrested in September 2004 in Old Town at a checkpoint set up by U.S. Customs & Border Protection, a division of the U.S. Department of Homeland Security, after border patrol agents found 140 pounds of marijuana in his car, according to court documents.

Attorney Leonard Sharon of Auburn said before the hearing on Friday that his client was considering whether to appeal U.S. District Judge John Woodcock’s ruling that upheld the constitutionality of the stop that resulted in Gabriel’s arrest.

Last month, Woodcock rejected U.S. Magistrate Judge Margaret Kravchuk’s recommended decision that granted Sharon’s motion to suppress the evidence seized in the search of Gabriel’s van.

She concluded that “the traveling public ought not be asked to endure checkpoint stops” so close to Bangor unless the government could “demonstrate in some fashion that the public interest sought to be advanced is, in fact, advanced to some degree.”

“[A]lthough I recognize that the intrusion upon an individual’s right to travel the highways without interruption is minimal,” Kravchuk wrote in her opinion, “the government simply has not demonstrated that its operation of the Old Town checkpoint appreciably advances any legitimate public interest.”

After a second hearing on the motion, Woodcock ruled in December that the temporary checkpoint set up in Old Town “passes constitutional muster” and was necessary for the government to be able to protect the public. He referenced as precedent a 1976 U.S. Supreme Court decision that dealt with similar roadblocks between San Diego and Los Angeles, Calif., several miles from the Mexican border.

Woodcock determined that “while the burden on Fourth Amendment rights remain small, the governmental need remains great … The United States-Canadian border is over twice as long as the United States-Mexican border, and likely presents as enticing an opportunity for smuggling weapons of mass effect or for individuals bent on destruction.”

The Maine Civil Liberties Union has criticized the stops and said that Woodcock’s decision threatens the “essence of liberty.”

Gabriel has been jailed since his arrest. Federal law requires that defendants who plead guilty to drug charges be held in the custody of the U.S. Marshal Service until their cases are resolved.

If Woodcock’s decision were to be overturned by a higher court, Gabriel could be released after serving all or a portion of his prison term. It is unlikely he would be released while his appeals were pending.