These IRS employees believed that they had implicit consent to ideologically profile nonprofit advocacy groups. Where did that come from? Lois Lerner—the IRS official who headed the division overseeing tax-exempt groups and who is now on administrative leave—certainly didn’t elucidate matters when she exercised her right against self-incrimination rather than testify before Congress on May 22.

What the Enron scandal teaches is that such implicit permission can be communicated by a toxic culture fostered by the company’s top brass.

Consider the tone that has been set by the person at the very top of the government the IRS serves. President Obama is the first president since Nixon to refer to political opponents as “enemies,” in October 2010, apologizing only after a week of intense criticism. Around the same time, he assailed conservative advocacy groups as a “threat to democracy.” As the nation’s top law enforcer, Mr. Obama singled out groups such as Americans for Prosperity by name and suggested they could be taking illegal foreign funds. That’s toxic culture from the C-Suite.