When his Caribbean Clipper chugged into an Alabama port with a shipment of Honduran lobsters, David Henson McNab never could have imagined the magnitude of crimes that federal prosecutors would accuse him of committing.

Some of McNab's lobsters were too small, prosecutors said, and all had been packed in plastic bags instead of the cardboard boxes required under Honduran fishing regulations. Viewing the shipment as an illegal import, they prosecuted McNab, a Honduran, under some of the toughest statutes in U.S. criminal law.

Although high-ranking officials in the Honduran government would insist that McNab, 52, had done no wrong, he was convicted in federal court in 2000 of money laundering and conspiracy and sentenced to 8 years in federal prison. He is jailed in Arkansas.

McNab's case now is before the Supreme Court, where some of the country's most elite appellate lawyers are asking the justices to reverse his sentence. But the case raises questions that go far beyond lobsters.

The justices are being asked to provide better guidance to lower courts in interpreting foreign laws--a job they frequently are called upon to do. And it would go beyond criminal prosecutions: The Justice Department, which is defending McNab's conviction, conceded in court papers that issues of foreign law regularly arise in civil cases.

A question of deference

In tax and immigration cases, for example, lower courts often must determine the validity of a marriage or an adoption abroad or the legitimacy of a child. When lower courts have been called upon to interpret the laws of another country, they have split on the amount of deference they must give to the views of foreign officials.

McNab's lawyers argue that the appeals court in his case flatly ignored the views of top Honduran officials, who have insisted he broke no Honduran laws and would not have been prosecuted there. They say the court's approach is out of line with the path taken by other appellate courts, including the 7th U.S. Circuit Court of Appeals in Chicago, which has given greater deference to the views of foreign officials in interpreting their laws.

Moreover, McNab's case comes at a time when several justices have increasingly favored giving greater weight to the views of other countries on how to interpret U.S. law. In a recent death penalty case, for example, Justice John Paul Stevens considered other nations' views to support a decision that executing mentally retarded criminals is unconstitutional.

The case also comes as the Bush administration is urging the Supreme Court to give it greater discretion to prosecute criminals and fight terrorism, arguing that it would use this new authority responsibly. McNab's lawyers say his case is an example of prosecutorial discretion run amok.

"How do you expect the court to take the government's word that it will use the powers it gets responsibly if you have these instances of abuse that are obvious even to lay people?" asked Miguel Estrada, McNab's lawyer. Estrada is the Bush judicial nominee who recently withdrew his name from consideration after Senate Democrats blocked his nomination.

The Honduran government, which has protested McNab's treatment and wants him released, has turned to former Solicitor General Seth Waxman to make its case to the Supreme Court. Waxman was the Clinton administration's top lawyer before the Supreme Court and is one of the nation's leading appellate lawyers.

Jody Manier Kris, a partner in Waxman's Washington law firm, said the case also is important for U.S-Honduran relations. She said it had "created a fair amount of uncertainty" among fishermen aware of McNab's long sentence.

But the Justice Department argues that it correctly prosecuted McNab for an illegal importing scheme and says Honduran agriculture officials confirmed that he had violated their regulations.

Those regulations were important in Honduras to protect its lobster fishery from overharvesting, as well as to ensure safe processing of fishery products, U.S. government lawyers argue.

The case arose in 1999, when agents of the National Marine Fisheries Service seized McNab's shipment in Bayou La Batre, Ala., after receiving an anonymous fax that some of his lobsters were too small and not packed in boxes in violation of Honduran law.

Federal agents and prosecutors sought help from the Honduran Ministry of Agriculture and Livestock in investigating the case. Officials in that agency assured the U.S. that McNab had violated Honduran law, the Justice Department says.

McNab was indicted a year later in federal court in Alabama for conspiracy and money laundering involving criminally derived property. His entire shipment--about 400,000 pounds of lobster worth $4.6 million--was deemed to be the proceeds of an illegal act.

The basis for the charges against McNab was the Lacey Act, which bars the importation of "any fish or wildlife taken, possessed, transported or sold in violation" of U.S., state or foreign law.

But Estrada said that Honduran officials never wanted to prosecute McNab, that the size and packing regulations didn't properly apply to him and that even if they had, he wouldn't have faced jail time. The Honduras regulations, even if they had applied to him, called for minimal fines, Estrada said.

In prosecuting McNab, U.S. lawyers took a federal statute and applied it to a situation Congress never intended, Estrada added, producing a "Draconian" sentence. The Lacey Act was designed, he said, to prosecute people who trap endangered game on safaris, for example, or who try to import rare animals for resale.

An Atlanta-based federal appeals court voted 2-1 to uphold McNab's conviction in 2003. It said that in arguing McNab had done no wrong, Honduras simply had changed its position after his trial. The lower court's conclusions on foreign law should be seen as "final," the appeals judges said, so people with "means and connections" don't persuade foreign governments to change the law in their favor.

`Strange position'

Dissenting U.S. Appeals Court Judge Peter Fay said the decision was a "strange position for members of the judiciary." He said the Honduran government had not changed its position and said McNab's conviction must be reversed because the Honduran courts had nullified one of the Honduran laws relied upon by the jury.