Last week Mike Sandvick, head of the Milwaukee Police Department's five-man Special Investigative Unit, was told by superiors not to send anyone to polling places on Election Day. He was also told his unit -- which wrote the book on how fraud could subvert the vote in his hometown -- would be disbanded. "We know what to look for," he told me, "and that scares some people." In disgust, Mr. Sandvick plans to retire. (A police spokeswoman claims the unit isn't being disbanded and that any changes to the unit "aren't significant.") In February, Mr. Sandvick's unit released a 67-page...