still with us, john, who covers the high court procedural roll call, and to bruce and jacnta singh. looking back over the 225 years since the writing of the constitution, if you concede the government is a breathing creature of the constitution, does practice create precedence, even if there hasn't been judicial decisions in this kind of thing, does the fact that we've. going on and doing this over time create the kind of precedence? >> the answer is both yes and no. if we take the most comparable battle of constitutional power, it enables congress to block executive action. it's existed some 60 years back to hoover, and invalidated hundreds of laws and encroaches on executive authority. on the other hand if you look at practice under taken from executive privilege we don't want to share information to congress. this happened in the nixon case, and the supreme court for the first time in 1974 addressed this question of executive privilege and really it doesn't protect you from a subpoena addressed to you from court. and it relied exclusively on george washington. it has adopted long