After warning federal prosecutors for two years, Judge Sam Sparks was fed up with the parade of nonviolent illegal aliens in the overburdened courtrooms in his Texas division. What he did next, said lawyers across the country, was astounding and unprecedented.

While other judges simply complained about a prosecution policy initiated by the Bush administration, the Republican-appointed judge in Austin issued an order challenging the U.S. attorney’s office to justify each illegal re-entry case brought before him.