The media echo chamber spent the week speculating about whether Special Counsel Robert Mueller can or will nab President Trump on obstruction-of-justice charges. All the while it continues to ignore Washington’s most obvious obstruction—the coordinated effort to thwart congressional probes of the role law enforcement played in the 2016 election.

The news that senior FBI agent Peter Strzok exchanged anti-Trump, pro-Hillary text messages with another FBI official matters—though we’ve yet to see the content. The bigger scandal...