Last year the United Kingdom finally appeared to be delivering on its promise to crack down on bribery and corruption. The Serious Fraud Office scored its first-ever successful conviction of a company for fraud and hoped that would telegraph a clear message to troubled corporations: Agree to a plea deal with us, or face prosecution and heavy penalties.

Now, however, that carrot-and-stick approach seems to be all stick and no carrot.

The SFO had wanted companies that discover bribery and corruption to turn themselves in, cooperate with an investigation, and agree to a plea. It also has a powerful means to ...