A few months ago, Mike Lynch, a wealthy British tech boss, walked out of a U.S. courtroom a free man. He had just won one of the biggest fraud cases in history, where he was accused of misleading Hewlett-Packard in a £8.64 billion deal. Lynch, who had been living under house arrest and wearing an electronic tag, was on the brink of a 25-year prison sentence. But against all odds, he was found not guilty.

Lynch, who’s sometimes called "Britain’s Bill Gates," had feared he might die in pri...