No matter how discredited and despised Wall Street executives may be across the country, their clout remains unrivaled on Capitol Hill. Judging from how much traction the American Bankers Association gets with lawmakers, you'd think it was an organization devoted to the interests of puppies and adorable children.

It's one thing for the banks to maintain a broken status quo, but it's another for them to work to break things further, by pushing an industry-friendly change through Congress in the midst of the crisis. Recently, in the case of mark-to-market accounting, that's just what they did.

The idea behind mark to market is pretty straightforward. If a bank owns, say, a mortgage-backed security, it must enter the value of that security in its books at the price the security can fetch on the market. If the security can get 80 cents on the dollar, it goes down as .80 in the books. If it can get only 20 cents, it goes down as .20. The standard enforces transparency by making banks sync their internal valuations with external prices.

Banks have whined about mark to market ever since it was codified in 2006. But it wasn't until last spring, as the subprime crisis gathered steam, that they began beating the drums for a change. They complain that the current panic has frozen the markets for many of their esoteric securities, artificially depressing the prices and therefore making their balance sheets look far worse than they really are.

The week after Lehman Brothers failed, as both conservative and progressive House members balked at the initial TARP plan, a number of lawmakers became convinced by onetime FDIC chair William Isaac that mark-to-market accounting was the culprit and that simply suspending or abolishing it was all that was needed to see us through.

They were ignored at the time, but the conservative noise machine ran with the idea (op-eds in the Wall Street Journal, rants on CNBC) and the banks kept working over Congress.

Finally, in a deft bit of bank-shot lobbying, the American Bankers Association, the Chamber of Commerce and others pressured the House Financial Services subcommittee on capital markets, insurance and government-sponsored enterprises to convene a hearing in March on accounting standards. There, members of both parties browbeat representatives of the independent Financial Accounting Standards Board for excessive fidelity to their precious rules. (Representative Randy Neugebauer of Texas: "Don't make us tell you what to do. Just do it. Just get it done.") Three weeks later, after a truncated process, the five-member FASB voted 3 to 2 for changes that would relax mark-to-market requirements. The two dissenting board members issued a minority report warning that the new rules could help hide losses and impair long-term economic growth.

So, in the midst of a global financial crisis largely abetted by the opacity of bank balance sheets, Congress, at the behest of Wall Street, bullied FASB into changing the rules so companies could make their balance sheets more opaque.

If you believe that collective manias can produce systematic mispricing (like the housing bubble), you won't find the banks' complaints implausible. But whatever drawbacks there might be with mark to market, the alternative--allowing banks to decide what their securities are worth--is certainly worse. "My fear is that you can't trust the banks to decide if the loan is going to be impaired," said a hedge-fund analyst who has studied the issue.

The technical merits of the accounting change aside, the procedural precedent--Congress stepping in to push a change in accounting standards--is far more disturbing. There aren't many industries able to manipulate the measurements used to assess their worth. "There's a heck of a lot of folks in Washington that mistake standards as policy," one FASB official told me. "It's not policy. It's about measurement."

Democratic Representative Alan Grayson of Florida, who opposed the change, made precisely this point during the hearing, joking that changing accounting rules to deal with depreciated assets was like dealing with cramped airline seating by redefining the size of an inch.

The partial relaxing of the standards was a victory for the banks, but they're still not satisfied; they continue to push the committee for another hearing and more rule-relaxing. And there is no organized, powerful opposition to their demands. In the case of mark to market, the banks faced the opposition of institutional investors who control more than $3 trillion, not to mention Tim Geithner and Ben Bernanke. They still won.

"These members of Congress are being told what it is the banks want them to hear without having an effective counter," says Allen Weltmann, a senior adviser at FASB. "It's not unique to this issue--it's typical of Washington on matters like this." In the absence of broad-based organized opposition, the president stands as just about the only possible counterbalance. The one legislative battle the banks have lost, over a credit card reform bill recently passed by both houses, was also the only bill on which the White House expended any real political capital. But the president, to put it charitably, tends to pick his battles, so relying on the White House isn't a strategy for success. Battles over the future of finance capitalism continue to be shockingly one-sided affairs. Unless and until this dynamic changes, nothing else will.