The mistrial in the Roger Clemens perjury trial last week was stunning. The cause of the mistrial was that the prosecution played video tape of Congressional testimony that contained hearsay and had already been ruled inadmissible. Here is a link to a Washington Post article discussing how it happened.

By all accounts the prosecutors are honest and simply threw this one behind the batter. So how does it happen? Easy. The prosecutors did not actually review the edited video excerpts before trial:

A review of transcripts and interviews with people knowledgeable about what happened reveals that federal prosecutors did not intentionally introduce barred evidence to the jury. Despite years of experience, two well-respected prosecutors had made a basic mistake and not carefully reviewed the videos they planned to show jurors.

Am I surprised that this could happen with experienced prosecutors? No. I am surprised that it happened on the second day of trial.

This is the type of mistake that I would expect to see more near the end of a long trial when the lawyers are running on fumes. But on day 2? That’s surprising. But not shocking.

Preparing for trial is all consuming. Much of the work is tedious and mundane—no matter how exciting the case is. Tasks like reviewing the edited video clips can keep getting pushed to the back burner while a lawyer works on other more pressing matters.

Sometimes these tasks end up not getting done. After all, the person who made the edits was careful and would have double checked, right? Wrong.

Remember Vincent Bugliosi’s 75% rule from his book Outrage about the OJ Simpson trial. Bugliosi’s theory is that 75% of workers are not good at their job—no matter what their job is. If you stop and think about it, he has a point.

The “don’t sweat the small stuff” theory is great. But during trial there is no small stuff.