Mark Schmitt provides some historical context for the current wiretapping scandal, and reminds us of the main practical reasons why allowing the President to circumvent the law is a bad idea:

Roughly speaking, there have been four great showdowns over abuse of executive power in modern U.S. history. … These episodes have certain themes in common. Yes, one of them is that they were all hatched in the first term of Republican presidencies and revealed only after reelection, but that’s not the answer I’m looking for. … First, all of them produced a backlash. … The lesson seems clear: In a constititutional system, those who want executive power to be protected and respected, should be especially wary of presidents who take it too far. … Second, all of them involved creating a zone of extreme secrecy in which decisions, and even the processes leading to those decisions, were kept secret not just from Congress and the Courts, but within the executive branch itself. … Third, in these zones of extreme secrecy, in which nothing ever has to be justified to anyone outside of the closed circle, all sorts of insanity flourishes. Personal obsessions take hold and are pursued unchecked. Ideas that would be too embarassing to explain to anyone seem to make sense and are carried out. This was true in every example, from the nutball Castro assassination schemes hatched in the CIA to the idea of firebombing the Brookings Institution in the Nixon White House, to the bizarre excesses of Iran-Contra, such as delivering a cake shaped like a key and a Bible signed by Reagan to the Iranian clerics. … Given what we know about these previous episodes in which the executive branch created zones of extreme secrecy, I think it’s quite likely that we will soon learn that the NSA domestic surveillance program involved much more than just tracking people who received calls from known al Qaeda suspects, something that I certainly wouldn’t object to. I don’t know what it will be—some have speculated that it involved monitoring journalists—but whatever it is, it was something that couldn’t be justified even within the administration.

This is a good counterpoint to the detailed legal readings provided by people like Orin Kerr: the fine-grain of the legal issues is very important, of course, but the political sociology of executive/judicial relations is a much broader topic than the proper reading of particular statutes. Mark reminds us that we have historical cases to remind us what tends to happen to the institutions of American government when its officials want to throw the cloak of secrecy over substantial parts of it—not just to keep things from the public but, as Mark says, to hide things from other parts of the executive.