All imports of Canadian cattle have been suspended since May 2003, when Canada's first domestic case of mad cow disease was discovered.

On Monday, a US Department of Agriculture rule is set to take effect allowing imports of Canadian cattle under 30 months old. Cebull is expected to rule sometime before then.

"If we're successful on Wednesday, it just means that they (USDA) will postpone that border opening until the merits of our case can be heard," said Shae Dodson, spokeswoman for R-CALF United Stockgrowers of America.

Separately, the US meatpacking industry is awaiting a decision by a federal judge in Washington, D.C., that would reopen the border to all Canadian cattle and beef, not just young animals and their meat.

Young cattle are thought to be least likely to carry mad cow disease. Humans can get a similar illness by eating contaminated beef.

American meatpackers, seeking greater supplies of cattle for slaughter, have sued USDA, accusing it of failing to establish scientific reasons for controlling trade.

On the opposite side of the issue, R-CALF lawyers are expected to argue that US cattlemen would suffer if Canadian cattle are allowed back into the American market. They claim USDA has ignored health risks from cattle raised in Canada, where three cases of mad cow disease have been diagnosed in the past 21 months.

But government lawyers will try to convince Cebull that Canada presents a minimal risk for the animal brain-wasting disease and that ample safeguards are in place on both sides of the border to protect US cattle and consumers.

Dodson said that either R-CALF or USDA is expected to appeal an adverse ruling by Cebull.