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If Massachusetts Senator John Kerry had escaped $500,000 in state taxes by docking his yacht in Rhode Island, the offense wouldn’t have been as serious as, say, plotting with the British against the Continental Army in 1780. But then, it was Kerry himself who upped the rhetorical ante against those who use tax loopholes for their own gain.

While running for president in 2004, Kerry frequently used the term “Benedict Arnold’’ to describe CEOs who move their companies’ operations out of the country to avoid paying US taxes. That hyperbolic characterization became embarrassing when it emerged that Kerry had accepted large campaign contributions from executives who fit the description, but Kerry was onto a real problem. As a senator, Kerry has admirably...