I'm not saying perjury doesn;t stand, just that people naturally forget to ask if the lie affects the outcome of the decision being made, or misleads the people involved in making the decision.
The senate committee hearing today had no purpose that i can discern. If the purpose was to probe Russian interference in the eleciton, questions about Comey and Trump are out of place, and the witness can lie about that line of question, with impunity.
Tell that to Scooter Libby.
He said he hoped the release of the memo would cause a Special Council to be appointed. How would that not be material? It shows he planned to interfere.