When is a fish like an incriminating document? Supreme Court will decide.

The US Supreme Court agreed Monday to take up a case posing a riddle: When is a fish like an incriminating financial report?

How the high court answers that question is critical to a case involving Florida commercial fisherman John Yates.

In 2007, Mr. Yates and his crew were cited for catching undersized red grouper in the Gulf of Mexico. The undersized catch was discovered after a fisheries enforcement officer boarded Yates’s boat, the Miss Katie, and began measuring the size of the fish in the hold.

The officer measured 72 fish as falling below the 20-inch minimum. He issued a citation to Yates, placed the undersized fish in a wooden box and instructed the captain that he would be met by another enforcement officer when he returned to port.

The fisheries officer then left.

Something strange happened on the way back to port. Apparently, many of the undersized fish managed to escape.

Ten days later back on land, the original enforcement officer re-examined the wooden box and discovered 69 fish measuring less than 20 inches.

When he initially filled the box, some of the 72 undersized grouper were as small as 18 to 19 inches. In contrast, most of the grouper examined on shore measured closer to the legal limit of 20 inches.

The officer became suspicious and investigators managed to extract an admission from a crew member, according to court documents.

The crew member said that Yates instructed the others on the boat to throw the significantly undersized groupers into the sea and replace them in the wooden box with other groupers that weren’t quite as small, court documents say.

Prosecutors were not amused. Rather than charge Yates with catching undersized grouper, they instead accused him of violating a federal criminal statute that prohibits the shredding of documents or other evidence in an attempt to obstruct a federal investigation.

The law is part of the Sarbanes-Oxley Act of 2002, which was passed by Congress in response to substantial shredding of incriminating financial documents related to the collapse of Enron.

Suddenly, the 64-year-old commercial fisherman was looking at spending up to 20 years in a federal prison, rather than paying a fine and serving a possible jail sentence. (He was ultimately sentenced to 30 days imprisonment and three years of supervised release.)

The fisherman’s lawyer objected to the obstruction charge and challenged it. A federal judge upheld the use of the so-called anti-shredding law, and that ruling was upheld by a federal appeals court panel.

In asking the Supreme Court to take up the case, Yates’ lawyer, Assistant Federal Defender John Badalamenti, argued in his brief that the lower courts’ expansive interpretation of the anti-shredding law would render it “overbroad, indeed limitless, in its reach.”

The anti-shredding section of the Sarbanes-Oxley Act “was never intended to prohibit the destruction of non-documentary, non-information items such as fish,” he said.

Mr. Badalamenti also argued that the lower courts had expanded the reach of the federal law in a way that “cedes more authority to the Executive Branch than Congress intended.”

Government lawyers disagree. They say that the federal law criminalizes intentional obstructive conduct involving “any record, document, or tangible object.”

“The court of appeals correctly concluded that fish are ‘tangible objects,’ ” US Solicitor General Donald Verrilli wrote in his brief urging the justices to reject the fisherman’s petition.

Yates “does not dispute in this Court that he directed the destruction or concealment of the fish in question, that he did so in connection with a federal agency investigation, and that he acted with obstructive intent. He argues only that a fish is not a ‘tangible object,’ ” Mr. Verrilli said.

Yates “is incorrect because a fish is indeed a ‘tangible object’ within that term’s ordinary and natural meaning,” the solicitor general added.

In a friend of the court brief, the National Association of Criminal Defense Lawyers (NACDL) criticized the Yates prosecution as an unconstitutional expansion of federal law and evidence of an “overcriminalization epidemic.”

“Overcriminalization, and the overfederalization of traditionally state offenses, places a growing burden on the administration of justice – often resulting in ludicrous federal convictions for offenses better resolved with civil penalties,” wrote William Shepard of West Palm Beach, Fla., in the NACDL brief to the court.

The nonprofit watchdog group, Cause of Action, also filed a friend of the court brief encouraging the high court to hear the case.

“This is quintessential overcriminalization,” wrote Washington lawyer Gus Coldebella.

“The reasoning underlying the [appeals court’s] opinion will continue to make a surprisingly broad range of unremarkable conduct a violation of federal law,” Mr. Coldebella said.

He said the court should take up the case to “properly limit” the scope of the statute and “halt the government’s unlawful overreach.”

The case is Yates v. US (13-7451). It will likely be set for oral argument next fall.