Ag In Ok said:
What the hell is a "colorable argument"?
Refers to the term "color of law." That's a part of US Code and more broadly a part of the English Common Law. It basically means to act under the authority of government. It may not be an expressed duty, right or privilege but the action is understood to be within the authority of the government.
The phrase refers to English officers of the crown who might not have been charged with a specific duty but were acting under the authority of the King by wearing his colors to enforce his will.
A colorable argument (and I'm sure a lawyer will mosey along to correct me if I'm wrong) is essentially a legal argument saying I have the right or ability to do this as an agent of the government and it's within my purview and it's legal.