Ol’ Ken Starr is advancing the ultimate defense on behalf of donnie (it’s known as the Charlie Brown/Coasters Defense):
“Why is everybody picking on me”?
(You have to be pretty old to get that reference so here's a link: Charlie Brown)
I will admit that Ol’ Ken also invoked Magna Carta, which was, I guess a way for him to sound erudite: Magna Carta was when the English Barons coerced the King (John I) to sign a document that said that he – the King – couldn’t spend money without authorization from the Barons.
So invoking Magna Carta sounds as if Ol’ Ken is making a case for control of the executive, not acquiescing to it.
I am missing how that contributes to the defense.
But he was scrambling to fill out the 500 word essay that he had been assigned.