President Obama said his Volcker Rule — part of the 2010 Dodd-Frank financial regulation bill — would stop commercial banks and investment banks from being gamblers, by banning “proprietary trading,” that is, trading with their own money. An investment bank is supposed to invest money for its clients, not be a hedge fund itself.

But there are — and have to be — some exceptions to this rule. These exceptions might block a humble entity from prop trading. But Goldman Sachs and JP Morgan are not humble institutions. They’ll find ways to keep being hedge funds. My brother John Carney at CNBC explained one way a big bank can still trade:

Now, of course, Goldman still trades. But it says it no longer engages in prop trading. Its trading is now focused on market-making, which means much more than buying and selling securities after receiving orders from customers. Goldman does not, actually, sit around and wait for customer orders. It actively creates positions — buys stuff — that it seeks to sell to clients. It takes trading risk but doesn’t call it trading anymore.

After JP Morgan lost a few billion, I explained this all in a different way:

Under the Volcker Rule, banks will still be allowed to hedge their risk. JPMorgan, as a core business, lends billions of dollars to big corporations. If these corporations start defaulting on their debts, JPMorgan is in trouble. The bank, accordingly, hedged against this risk …

You can see why regulators wouldn’t want to infringe on hedging by banks. But you could also see how a clever bank could use hedging exceptions as a loophole through which to engage in the same profit-seeking proprietary trading the Volcker Rule intends to stop.

Now check out the language Goldman Sachs alumnus and millionaire Obama fundraiser Jon Corzine used when describing the prop trading he was undertaking at MF Global (which wasn’t even covered by the Volcker Rule). Basically, he called it “customer facilitation.”