Some important national policies have been adopted lately, on diverse fronts: The Bush administration has made a stunning claim of unilateral power to pick up anybody the military declares to be an "enemy combatant" and jail him or her indefinitely. The president has announced an unprecedented policy of launching pre-emptive military strikes whenever he sees fit against Iraq and any other nation or terrorist group he deems threatening. The Supreme Court has ruled that the death penalty can be imposed only by juries, not by judges, and that retarded murderers may not be sentenced to death at all.

Whatever the merits of these policies, a common feature that surprises nobody today would have amazed the Framers of the Constitution: Congress had no role in developing any of them. That’s the same Congress in which the Constitution vests "all legislative powers herein granted," including the power "to declare war."

These are but the most recent examples of two decades-long trends: Presidents (especially this one) and justices (especially the current nine) have aggressively expanded their powers. Meanwhile, the role of Congress shrinks, with the Senate acting as an obstacle course and the House ever more ideologically polarized and incapable of reaching sensible, muscular compromises on controversial issues.

This is not good for the country. It threatens the vitality of the checks and balances that the Framers designed to guard against executive or judicial tyranny. And it undermines the popular legitimacy of the many policies that have been imposed on the nation by the president or the judiciary with neither democratic debate nor input from the elected representatives of the people.

Presidential power is bound to expand in wartime, of course, given the inherent inability of any large legislative body to react quickly to enemy attacks. But this war may never end. So it is worrisome to see Bush eschewing the approach of his predecessors-including his father-who saw Congress as an indispensable, if sometimes balky, partner in waging war.

Even before September 11, the Bush administration was singularly aggressive in pushing the envelope of presidential power. Bush ignored Congress in renouncing the 1972 Antiballistic Missile Treaty and the 1997 Kyoto Protocol on global warming. The administration went to the mat to block fairly routine congressional and General Accounting Office inquiries, and it put up barriers to the disclosures mandated by the Presidential Records Act of 1978. These acts evidence a presidential passion for secrecy unseen since Watergate. The message to Congress and the media was, in essence: "We know what we’re doing, and it’s none of your business."

Then came September 11, and the sudden need for a strong, swift presidential response. Bush responded admirably, in Afghanistan and elsewhere. But since the administration finished wrangling with legislators to get a somewhat watered-down USA-PATRIOT Act through Congress last October, the president and his people have unwisely tried to run the war against terrorism all by themselves.

Bush consulted no congressional leaders before authorizing trials of suspected noncitizen terrorists by special military commissions last November. One result of this unilateral approach was that Bush’s "military order" was so poorly drafted as to alarm many who would have supported a carefully vetted legislative proposal-or even a presidential order-if it had specified decent fair-trial guarantees. The administration has cloaked its detentions of hundreds of Islamic noncitizens in unprecedented, blanket secrecy, which it implausibly defends as necessary to defend the nation against new terrorist attacks. And now, in a June 19 legal brief, comes the sweeping claim of power to incarcerate any alleged "enemy combatant"-a vague, undefined, dangerously open-ended term in the current shadow war against terrorist infiltrators who seek to strike us from within.

The elected representatives of the people should be publicly debating this radical assertion of executive power, and whether some sort of preventive detention policy is necessary, and how to guard against error and abuse. At the same time, Congress should be open to giving the president any new investigative powers he really needs, and perhaps creating a special federal court to handle the cases of suspected international terrorists arrested on the domestic front. Instead, Congress has been largely passive. And while a few judges have challenged aspects of the administration’s detention policies, those decisions are on appeal; the judiciary has not been a very sturdy bulwark against executive overreaching during past wars.

The judiciary has, on the other hand, proven to be as aggressive as any president in extending its own domain, exuding an ever-more-naked penchant to legislate in the guise of constitutional interpretation. The liberal Warren Court got this ball rolling. But now the Court’s three conservatives and two centrists seem equally ready to abandon judicial restraint whenever they feel strongly about something.

The result is that "differently constituted majorities of the Court wind up substituting judicial judgments-sometimes liberal, sometimes conservative-for legislative judgments at an unprecedented rate," as Walter Dellinger, the moderate-to-liberal former Clinton solicitor general, wrote recently in Slate. "Because this Court’s overall philosophy is somewhat politically moderate, the effect of its extraordinary assertion of judicial supremacy has not made a striking impact-yet. Just wait a decade."

Judicial supremacy? Consider Atkins v. Virginia, the June 20 decision exempting mentally retarded murderers from the death penalty. While the result is pleasing to many of us, the decision has the inconvenient feature of being unsupported by the Constitution’s text or the Framers’ designs. "Seldom has an opinion of this Court rested so obviously upon nothing but the personal views of its members," as Justice Antonin Scalia wrote in dissent.

Indeed, the majority opinion was an embarrassment to thoughtful critics such as Dellinger, who observes, "Congress would be a more appropriate national institution than the Court to review and restrict questionable state executions." The four liberals and two centrists in the majority purported to divine a "national consensus" against executing retarded killers from the rejection of such executions in recent years by 18 of the 38 capital-punishment states. But 47 percent does not a consensus make. The only consensus was the view of six unelected judges that they know best.

The imperial proclivities of the executive and judicial branches are not the only causes of dwindling congressional clout. The most fundamental cause is that Congress so often seems incapable of the compromises necessary to contribute usefully to the resolution of ideologically charged issues.

One reason is that Congress is so evenly divided. Another is the need for 60 votes to get anything through the Senate. A third, more regrettable reason is that the House has become so ideologically polarized, with most members beholden either to the Democratic left wing or to the Republican right wing. This comes from the egregious gerrymandering that has made as many as 90 percent of the 435 House districts strongly Republican or strongly Democratic-the better to protect incumbents. Such gerrymandering "lines up the parties with their ideological extremes, leaving underrepresented the roughly 50 percent of the electorate that stands nearer the political center," as John Harwood wrote in a June 19 analysis in The Wall Street Journal. In such a body, compromise is elusive.

Congress still keeps busy, of course. It taxes, spends, investigates, leaks, speechifies, stalls nominees, chases campaign contributions, and more. But as long as Congress is seen by the president, the justices, and much of the public as an unproductive pit of partisan bickering and grandstanding, and as long as it leaves terrorism to the president and social issues to the judiciary, we will not have the "republican form of government" that the Framers envisioned.

I have two errors to correct. First, I erred in stating in my March 16 column that if one assumes "that Al Qaeda terrorists are at least 100 times as likely to be from the Middle East as to be native-born Americans, and that fewer than 5 percent of all passengers on domestic flights are Middle Eastern men, it would follow that a randomly chosen Middle Eastern male passenger is roughly 2,000 times as likely to be an Al Qaeda terrorist as a randomly chosen native-born American." In fact, the percentage of passengers who are Middle Eastern has no bearing on the odds that any one of them will be a terrorist.

Second, I erred in my May 11 column in describing Bush judicial nominee Miguel Estrada as having a "rags-to-legal-stardom life story." In fact, the Honduran-born Estrada grew up in modest, but not abject, circumstances.