Can the president make fraud and theft legal? How about assault? Cocaine use? Perjury?

You’d have to conclude he can — and that we have supplanted the Constitution with a monarchy — if you buy President Obama’s warped notion of prosecutorial discretion. Tonight, Mr. Obama will unveil his executive order granting amnesty to millions of illegal aliens. According to news accounts, the criminal-law doctrine of prosecutorial discretion is the foundation of the president’s legal theory. It is the source of what he purports to be his authority to decree that these aliens have lawful status, a power our Constitution gives only to Congress.