Today as the Supreme Court continues to hear arguments on the constitutionality of ObamaCare, the President made this remark:
Ultimately, I'm confident that the Supreme Court will not take what would be an unprecedented, extraordinary step of overturning a law that was passed by a strong majority of a democratically elected Congress
Were the Court to rule the law is indeed unconstitutional it would hardly constitute an unprecedented or extraordinary act.
See the following government documents for lists of Acts of Congress (last updated 2002) struck down as unconstitutional by the Supreme Court (158 are listed): ACTS OF CONGRESS HELD UNCONSTITUTIONAL IN WHOLE OR IN PART BY THE SUPREME COURT
Also see: STATE CONSTITUTIONAL AND STATUTORY PROVISIONS AND MUNICIPAL ORDINANCES HELD UNCONSTITUTIONAL OR HELD TO BE PREEMPTED BY FEDERAL LAW (1789-2002)
Below is a breakout summary (via Marcia of answers.com) of the records contained in the above links:
1789-2002 Acts of Congress Held as Unconstitutional..............................158
1789-2002 State Statutes held unconstitutional......................................935
1789-2002 City Ordinances held unconstitutional....................................222
1789-2002 State and City laws preempted by Federal laws.......................224
Total State, Local and Federal Laws Declared Unconstitutional................1,315
Total State and Local Law Preempted by Federal Laws..............................224
Total Laws Overturned, all governments..............................................1,539