The pressing, constitutional question wasn't whether Nixon himself had drawn up the harebrained scheme to break into Democratic Party offices inside the Watergate apartment complex in 1972. It was whether Nixon knew his underlings were running a criminal enterprise from inside the executive offices. The same holds true for Christie today.
Despite the hundreds of hours Republican congressional committees have spent trying to ferret out Obama scandals, and the thousands of hours the right-wing media have devoted to that same goal since 2009, Christie's office last week produced the type of smoking-gun document that Obama's critics can still only dream about. But of course they'll keep dreaming.