After signing the new law requiring police to check out people who may be illegal immigrants, Arizona Gov. Jan Brewer was asked how the cops are supposed to know when someone should be screened. "I don't know," she replied. "I do not know what an illegal immigrant looks like." And she's not alone in her ignorance. As Steve Chapman notes, several of the new law's provisions are unclear. In other words, Chapman writes, we will find out what the law means after it takes effect, not before.