It's easy to suppose that the Republican wave will put President Obama on the defensive. But that would be a mistake. House Republicans may repeat then-Speaker Newt Gingrich's blunder and shut down the government, but their other weapons are distinctly small-bore. The new congressional committee chairmen will predictably launch investigations into real or imagined scandals, but this will cause political embarrassment, nothing more.
In contrast, presidents control a formidable arsenal that often permits them to act independently of Congress. They can take military action against al-Qaeda in Yemen or other places to pre-empt a terrorist attack, or invoke sweeping emergency measures if an attack succeeds.
They can also act unilaterally to transform domestic policy. This was impossible during the first 150 years of the republic. Until the New Deal, the president had no permanent staff. He governed through his Cabinet, largely composed of independent potentates who often resisted his demands. But in 1939, President Franklin D. Roosevelt persuaded Congress to give him six special assistants. Seventy years onward, these six have become 500, and presidents of both parties have vastly increased their powers.
President Clinton took it a decisive step further. Without gaining statutory permission, he authorized his staff to issue policy directives to the rest of the executive branch. After the Democrats lost Congress in 1994, Clinton used these new powers to maximum effect. He typically went into the pressroom himself to announce his staff's regulatory initiatives with great fanfare. By directing the bureaucracy to implement his program, he could make an end-run around Congress, but at a grave risk to the rule of law. As Elena Kagan put it when she was a Harvard law professor: "Presidents, more than agency officials acting independently, tend to push the envelope when interpreting statutes" - generating a tendency toward "lawlessness."
These regulatory power grabs were facilitated by another development that began in the Nixon administration. Over the last generation, presidents have created an elite corps of lawyers who have powerful incentives to tell them what they want to hear.
Until President Nixon's time, the Justice Department held a virtual monopoly on legal advice to the chief executive. But Nixon's White House counsel, John Dean, took the unprecedented step of creating a small legal staff to compete with Justice during the Watergate era. This staff has grown to include about 40 extremely able lawyers - but all gain their jobs through political connections. This also is increasingly true of the 25 lawyers who serve in the special division of the Justice Department, the Office of Legal Counsel, that continues to advise the president. This highly politicized process led to legal documents like the Bush-era "torture memos" that defended the indefensible.
Unfortunately, the current administration has done nothing to change this arrangement. Obama loyalists have simply replaced Bush loyalists in key legal positions. Like their predecessors, they are in a position to generate impressive-looking legal documents to support presidential assertions of unilateral power at home and abroad. Presidents Clinton and Bush repeatedly made use of this legal tactic after they lost control of Congress in 1994 and 2006, respectively. It will require remarkable self-restraint from Obama to reject this time-tested formula for success during political adversity.
And yet the president should pause before proceeding down the path blazed by Clinton and Bush. Obama should listen instead to voter anxieties about the arbitrariness of big government and reform the White House counsel's office. He should work with Congress to create a new institutional framework that encourages the president's lawyers to say "no" when their professional judgment tells them their boss is moving into forbidden legal territory.
Forty years ago, historian Arthur Schlesinger famously warned Americans about the dangers of an imperial presidency. These imperial dynamics have accelerated in the recent past. The challenge is to develop a broad range of pragmatic reforms that will reinvigorate America's constitutional tradition of checks and balances - and make them a key element of the next political agenda.
If this reform effort fails, past presidential misadventures during Watergate, Iran-Contra and the "war on terror" may only serve as prologue to more terrible abuses of presidential power in the generation ahead.
Bruce Ackerman is a professor of law and political science at Yale and the author, most recently, of "The Decline and Fall of the American Republic." He wrote this for the Los Angeles Times.