Justice Samuel A. Alito Jr. got a laugh last term when he posed a hypothetical historical inquiry that he said could hold the key for some in determining whether it was constitutionally kosher to ban the sale of violent video games to minors.

“I think what Justice Scalia wants to know is what James Madison thought about video games,” Alito said during oral arguments.

An upcoming case on the court’s docket about who holds claim to the nation’s riverbeds may depend on what appears to be a more discoverable answer to another historical question:

What did Lewis and Clark think?

PPL Montana v. Montana asks the court to decide who owns the lands below three Montana rivers and pits the state against a company that operates three hydroelectric dams along the waterways. Both sides say the outcome could affect the control of riverbeds throughout the nation, especially in the West.

And both sides claim that the 1805 journals of the great expedition to the Northwest conducted by Meriwether Lewis and William Clark lend credence to their arguments.

(It is another pair — Clement and Garre — that have drawn the attention of Supreme Court insiders: It will be the first time that Paul D. Clement and Gregory G. Garre, both former solicitors general in the George W. Bush administration, have argued on opposite sides.)

Besides the questions of law, the justices will be called upon to act as historians, trying to discern the navigability of the rivers at the time Montana became a state in 1889. It starts with Lewis coming upon the Great Falls of the upper Missouri River in June 1805.

“My ears were saluted with the agreeable sound of a fall of water and advancing a little further I saw the spray arrise above the plain like a column of smoke,” Lewis wrote, adding that he heard “a roaring too tremendous to be mistaken for any cause short of the great falls of the Missouri.”

The Supreme Court determined years ago that states own the title to rivers that were navigable at the time of statehood. The question now is whether that ownership is different in segments of the river impassable because of falls or other impediments, or is determined by looking at whether the river as a whole is navigable, evidence of which can be based on present-day use.

The Montana Supreme Court decided the latter. Even though the land on which PPL Montana operated its dams was never treated as belonging to the state — Montana had never claimed it until private citizens acting on the state’s behalf sued in 2003 — the court said it belongs to the public.

It agreed that PPL owed back rent — $53 million and counting.

Clement argues on PPL’s behalf that the Montana court disregarded “long-settled understandings and the overwhelming weight of historical evidence” to allow the state “to effectuate a massive land grab.”

The federal government agrees with the company, saying it retains title to land where a waterway is not navigable and may issue permits for its use.

But Garre argues for Montana that the state court simply “reached a judgment that would surprise few Montanans: The rivers at issue are navigable, and Montana therefore took title to the riverbeds at statehood, in public trust for Montanans.”

Accepting PPL’s test would “upset centuries-old expectations and call into question the navigability of rivers not just in Montana but throughout the United States,” Garre wrote.

Twenty-six states are supporting Montana.

Both the state and the company say Lewis and Clark’s experiences make their case.

Clement points out that the expedition never even attempted to navigate one of the rivers at issue, and that the record shows Lewis and Clark bypassed the 17-mile Great Falls Reach of the Missouri “not out of convenience, but out of necessity — the stretch was impassable.”

Historians who agree with PPL said the state’s evidence of the commercial history of the rivers is in part based on notoriously unreliable frontier-era newspapers with boosterish and fabricated tales of “28-pound radishes and steamboat traffic between Denver and the Gulf of Mexico.”

Montana replies with Lewis’s observation that he did not believe “that the world can furnish an example” of how rivers can run through such mountainous country as Montana and yet be “so navigable as they are.”

It is beyond dispute that the rivers played an important part of the new nation’s economic development, Montana argues.The state’s supportive historian is Stephenie Ambrose Tubbs, who has written extensively about Montana and is the daughter of Lewis and Clark scholar Stephen Ambrose.

“For those of us who have spent our lives on these Rivers, retracing Lewis and Clark’s historic footsteps,” she told the court in a brief, a piecemeal approach to ownership is threatening.

And, for those who look to original meaning, she proposed that the court affirm the Montana Supreme Court, which she said recognized “that these rivers were navigable, as that term was understood by President Jefferson and the Founders before him.”