A little-known U.S. law is creating confusion for Canadians crossing the border to purchase tickets for the record Powerball lottery jackpot draw.

Like thousands of other Canadians, Lisa Yuen, a resident of Burnaby, B.C., headed across the border last week, to buy tickets ahead of the last Powerball draw held Saturday.

But Yuen was surprised when she received a strict warning from a U.S. border guard, about a law of which she'd never heard.

"We got a bit of a lecture from the border guard, saying that you can buy a ticket, but you can't take it back into Canada and then come back to the United States," she told CTV Vancouver.

U.S. law does not forbid foreigners from buying tickets or winning the lottery, and according to the Powerball website, "You do not have to be a citizen or a resident to play the game. You can be a tourist."

But if a Canadian buys a ticket, takes it home, and then tries to bring it back into the United States, they risk violating a law that forbids importing "immoral articles."

According to the law, "all persons are prohibited from importing into the United States from any foreign country any … lottery ticket, or any printed paper that may be used as a lottery ticket, or any advertisement of any lottery."

The only exception is for “any lottery ticket, printed paper that may be used as a lottery ticket, or advertisement of any lottery, that is printed in Canada for use in connection with a lottery conducted in the United States.” But Powerball tickets are not printed in Canada.

And though the lottery section of the rules may seem obscure, Yuen wasn't the first Canadian to run into the issue.

In December, U.S. border guards seized nine B.C. lottery tickets from a man trying to cross the border, and confiscated his Nexus card during the incident.

Ahead of the Powerball draw Wednesday, for a jackpot estimated to be at least US$1.5 billion, the rule is raising questions for lottery players and officials on both sides of the Canada-U.S. border.

"It is concerning," Jana Jones, the director of legal services at Washington's Lottery, said. "It appears the Washington border patrol is not allowing Canadians to bring (tickets) back in."

When asked if border officials would be able to seize a jackpot-winning ticket, she replied "It appears so."

Still, the law isn't stopping thousands of Canadians from trying their luck.

After buying $34 worth of tickets in her cross-border trip last week, Yuen said that, for her, the $1.5B jackpot is worth the risk.

"It's a chance I'm willing to take," she said.

With files from CTV Vancouver