In December 2003 a Holstein dairy cow in Washington State tested positive for BSE (bovine spongiform encephalopathy, or mad cow disease), the first case discovered in the United States and the second native case in North America. (Canada confirmed a third and then a fourth case in early January 2005.) The U.S. BSE cow and the first two Canadian cows were born in Canada, before both countries banned, in 1997, the practice of feeding most ruminant material back to ruminants, including cattle. The latest Canadian case was in a cow born in March 1998. In all four cases, BSE-contaminated feed is considered the most likely cause of infection. Lower-risk Canadian beef has been permitted into the United States since August 2003. As the two new BSE cases were emerging, USDA published a final rule, on January 4, 2005, to allow younger live cattle and other additional Canadian ruminant products to enter, effective March 7, 2005. Numerous producers and several lawmakers are among those now urging USDA to retract or delay the rule. Congress has 60 legislative days to review and consider whether to override it; hearings have been scheduled. Most countries banned U.S. beef after the December 2003 U.S. discovery. ...