Pivoting from their failed Russia-Trump collusion narrative, Democrats and the press corps have discovered a new political villain: William Barr. They claim the Attorney General is misleading the public, but their real goal is to warn Mr. Barr from following through on his promise to investigate abuses by the FBI and Obama Administration officials.

The rap is that Mr. Barr didn’t tell the truth about special counsel Robert Mueller’s report when he summarized its conclusions in late March. “It’s a disgrace to see an Attorney...