There is no such thing as concealment. Commit a crime, and the earth is made of glass. Commit a crime, and it seems as if a coat of snow fell on the ground, such as reveals in the woods the track of every partridge and fox and squirrel and mole. You cannot recall the spoken word, you cannot wipe out the foot-track, you cannot draw up the ladder, so as to leave no inlet or clew. Always some damning circumstance transpires. The laws and substances of nature, - water, snow, wind, gravitation, - become penalties to the thief.
From Compensation, Essays, First Series, by Ralph Waldo Emerson
Today, the Attorney General of the United States failed to appear before Congress. It is conjecture that he did not because he feared being questioned by the House Judiciary Committee. The signal goes well beyond this conjecture - what if every citizen refused to appear before a Congressional body? What if attorneys recommend that witnesses refuse to appear? This is the larger precedent. When the AG of the United States of America refuses to appear, then it is not only disrespectful of Congress, but signals that the he doesn't believe the laws related to his appearance are enforceable.
Should citizens take note?
Yet, he "cannot recall the spoken word ... so as to leave no inlet or clew."
If there is wrong doing, it will be known soon enough.