Big banks are in the spotlight once again for a host of alleged misdeeds including tax evasion, money laundering, price rigging and manipulating foreign exchange rates. But despite the seriousness of these accusations, federal prosecutors have yet to file criminal charges against a senior bank executive.

By contrast, hundreds of officials were jailed during the savings and loan crisis and past corporate fraud cases including Enron and World Com. The big difference between then and now comes down to the size of the defendants. The Department of Justice has deemed senior officials of the country's biggest banks too important to charge.

In the past, prosecutors relied on deferred prosecution agreements to settle criminal cases against big. These agreements gave banks conditional amnesty upon paying a fine and promising to implement reforms in the future. Public concern regarding this lenient treatment has since forced the DOJ to insist that big banks pleading guilty to criminal violations. But this tougher stance ismostly for show.The entities that plead guilty are lower-level, nonbanking subsidiaries. Thus the parent company’s banking licenses are not at risk. And of course, executives get off scot-free.

Crimes are committed by humans — not organizations. If prosecutors decline to jail or even fine individuals, criminal law hardly works as a deterrent.

Banking is a team sport. Someone is always either calling the plays or condoning the play selection. If bank management truly didn't know about their employees' misdeeds, they should have known about it. And if institutions are too big and complex for senior officials to know what their underlings are doing, as HSBC chief executive Stuart Gulliver recently implied, they should scale back. 

When we allow managers to plead ignorance as a defense for wrongdoing, we encourage further ignorance and illegal activity.

Prosecutors have struck a Faustian bargain with too big to fail banks. In exchange for declining to file charges against senior management, they get a quick plea, substantial fines and the appearance of being tough on crime. Everyone wins — except the public.

Regulators such as Federal Reserve Governor Daniel Tarullo are taking note of the problem. They insist that big banks must improve oversight to reduce illegal employee behavior and bolster their culture. But the problem is criminal, not cultural, and regulators are poorly suited to handle criminal activities. The DOJ should be leading the charge.

There is a simple way to stop bankers from violating the law, and it doesn't require new laws or breaking up the largest financial institutions. The DOJ simply needs to begin charging the bankers who commit crimes instead of focusing solely on the firms for which they work. When appropriate, prosecutors can also assess monetary fines and damages against the banks as restitution.

This is not about bashing big bankers or punishing them for bad business decisions and excessive risk-taking. It's about eliminating the de facto immunity from criminal charges that bankers currently seem to enjoy.

By prosecuting individuals who are responsible for misdeeds, the DOJ can curtail illegal activity and restore public trust in big banks — and in the law itself.

J.V. Rizzi is a banking industry consultant and investor. He is also an instructor at DePaul University Chicago.