Reading through the President's memo to the Senate regarding impeachment, and I'm baffled by this statement that, by including the terms "treason and bribery" in the Constitution, the Framers were stating that impeachment can only occur when there is a violation of settled law... 
At the time the Constitution was written (and for some time after), there was no federal statute criminalizing bribery.
So the only plausible way to read this segment of the memo is as a concession that the violation of a common law crime can be enough for impeachment.
So the only plausible way to read this segment of the memo is as a concession that the violation of a common law crime can be enough for impeachment.
Why does that matter? Because as @nikobowie points out, abuse of power was a common law crime.
So, in trying to argue that the articles of impeachment are insufficient, the President's lawyers said something that is either false, or helps the other side.
So, in trying to argue that the articles of impeachment are insufficient, the President's lawyers said something that is either false, or helps the other side.
