Politicians are too short-sighted and vote-hungry to say such things. They want a "credit card holders' bill of rights" that would prohibit certain billing practices, like raising interest rates on existing balances. The House could approve the "bill of rights" this week.

Understandably, these billing practices endear themselves to no one, but competition makes the worst of them far less common. And as for raising rates, revolving credit means that a balance is a fresh loan each month; as the terms state, the rate can change. If issuers can never raise rates on existing balances, even when economic conditions change, they will be likely to charge everyone a higher rate to make up for the risk.

Todd Zywicki, a professor at George Mason University Law School and an expert on consumer credit, points out that the credit-card industry is highly competitive. The web is full of sites that permit easy comparison shopping. Competition has driven banks to more precisely match consumer costs to individual risk. In earlier days, every cardholder paid higher interest rates than today and an annual fee (a way around usury laws). Now, annual fees are largely gone. Rates are lower. Late and over-the-limit fees are unpleasant, but they aren't charged until a cardholder's conduct triggers them. This is not to say credit-card companies never abuse customers, but as Zywicki notes, "[T]here are ample tools for courts and regulators to attack deceptive and fraudulent practices on a case-by-case basis."

Politicians assume we are ignorant about credit-card terms. However, Zywicki points to evidence that people who carry credit-card balances are aware of the interest rate they're paying, and "those who carry larger balances are even more likely to ... comparison shop."

The "bill of rights" seems designed to prevent people from getting themselves in over their heads. That motive is honorable, but government has never been very good at such protection. The law of unintended consequences cannot be repealed, and what government gives with one hand, it inadvertently takes away with the other. Increasing the banks' costs will make it harder for poorer people to get credit cards, and that will only push them into costlier forms of debt, like payday lenders.

I've never understood how the poor are helped by limiting their choices.