The U.S. government has yet again hit the debt ceiling -- a limit that was increased by $450 billion to a whopping $6.4 trillion just last year. The lack of fanfare surrounding the event reflects that the debt ceiling is now little more than a whisper of a reminder that there is a downside to excessive government borrowing, not the closing of the credit line it was intended to be. Given the return of structural budget deficits and the looming costs associated with the coming retirement of the baby boomers, it is high time to not only strengthen the debt ceiling, but to expand it as well.

Because of the negative economic consequences of too much government debt and the basic unfairness of passing along the unpaid bills to future generations, debt ceilings in one form or another have existed in the United States for more than 200 years. In principle, when the ceiling is hit, the government cannot engage in further borrowing and must adjust its taxing and spending policies accordingly.

In practice however, to get around the limit, government officials have devised a host of accounting tricks that make the Ken Lays of the world look like amateurs. In recent years, administrations have employed various techniques from holding off on investing money owed to government pension funds, to redeeming government-held securities prematurely, to permitting the issuance of special securities not counted toward the debt limit.

Put simply, government obligations that count toward the debt ceiling are replaced with others that don't, and borrowing continues based on the accounting loopholes. Once the debt crisis is over (inevitably, the debt ceiling is lifted after politicians have made a string of heartfelt speeches about the importance of responsible budgeting) the government accounts are replenished with what they are owed.

As the debt ceiling becomes increasingly meaningless, experts have suggested the mechanism be foregone altogether. U.S. Federal Reserve Chairman Alan Greenspan, for instance, has testified that since the choices about tax policy and spending are made during the budget process, providing mismatched debt restrictions is like "trying to restructure arithmetic."

But repealing the debt limit would remove one of the few remaining checks on budgeters. As the past months have shown, whether there is room in the budget or not, tax cuts and new spending prove enticingly tempting to politicians. Stronger, not weaker, mechanisms are needed to add a semblance of balance to the budgeting process.

Either of two relatively straightforward changes would do the trick. One option is for Congress to expand the reach of the debt limit to include the markers that track the debt that has been taken out of and will have to be repaid to government trust funds once any given debt ceiling crisis has ended. Since obligations to repay the trust funds are in essence IOUs from the government, the same as more explicit government debt, it makes no sense to treat them differently for accounting purposes. Or, Congress could statutorily require that receipts owed to government trust funds be deposited immediately and that redemptions take place only when necessary to meet the program's funding needs and not be tolerated as part of creative accounting schemes.

Congress is not fond, however, of straitjacketing itself without including a quick release, and a release in this instance is necessary since even flirting with the prospect of a government default triggered by a meaningful debt ceiling could be disastrous for financial markets. Rather than sneaking certain kinds of debt under the ceiling's radar, automatic spending reductions and/or tax increases should be built directly into the budget, to be triggered just short of when the ceiling would be hit. The debt ceiling could always be increased, as it can be now, but the choice to do so would be made fully transparent.

If politicians were serious about accounting for the government's debt, they would consider expanding the debt ceiling further. Neither the $3.7 trillion owed to the public nor the total $6.4 trillion government debt begins to paint the full picture of the government's books. There is another $3 trillion in liabilities for insurance programs and federal pension and health care liabilities on the government's balance sheet that should be included in debt limits. Even more worrisome, the present value of the nation's unfunded liabilities to Social Security and Medicare is estimated to be in the neighborhood of $17 trillion -- a growing obligation that is not constrained by any debt management tool. Placing a similar ceiling on unfunded liabilities would help impel Congress to enact needed reforms rather than pushing the choices into the future.

Improving the effectiveness of the current debt ceiling would at the very least be a good first step in controlling total government liabilities. Certainly, given all the emphasis on honesty in accounting these days, Congress should be willing to strive for the same improved standards when it comes to cleaning up its own books.