In his long-awaited report, special counsel Robert Mueller found that the evidence failed to establish “collusion” between the Trump campaign and Russia. In addition, he did not find that President Trump committed obstruction of justice, the only other offense discussed in the report.

By contrast, independent counsel Kenneth Starr, in his 1998 report, established that President Clinton perjured himself during a civil deposition, conspired to obstruct justice, violated criminal prohibitions against witness tampering, and perjured himself before a grand jury.

When congressional Republicans commenced impeachment proceedings against Clinton, congressional Democrats and their media allies were outraged. Even though the evidence established that Clinton committed multiple felonies, each of which related to obstructing justice, they insisted that his conduct did not warrant impeachment.

Yet now, some congressional Democrats and some in the media contend that Trump should be impeached for obstructing justice even though a multi-year, hugely expensive investigation has failed to find that he committed that crime or any other. I don’t see a principled basis on which this position can be reconciled with the nearly unanimous opposition of Democrats to Bill Clinton’s impeachment in the 1990s.