In 1999, I was interrogated on suspicion of being an Irish Republican Army terrorist plotting to assassinate Baroness Margaret Thatcher with a letter bomb. I was startled by a phone call from the police chief of the Maryland town where the former prime minister was going to attend a conference that weekend. He said, “The bomb squad’s robot just about to throw this heavy package addressed to you at the hotel into the Chesapeake, but then I figured I’d give you a call to find out if you can explain what it is.” This was not wholly unreasonable because in 1984 the IRA ...