The Supreme Court decision Wednesday limiting credit union membership to people with something in common found a 1982 federal regulation to be in conflict with the underlying 1934 law. Now it’s up to Congress to fix the underlying law.

The 5-4 ruling essentially says members of a credit union must have a common bond of employment or community. Since credit unions of less than several thousand members lack the resources to extend any substantial amount of credit, this ruling will have a significant impact in Maine, a state of small towns and small business, a state with an extraordinarily strong affection for these home-grown financial institutions — 89 credit unions with 561,000 members.

Federally chartered, non-profit, member-owned credit unions came into being during the Great Depression, when banks were failing and faith in banks was low. Credit unions were a minor player in the industry, a self-run alternative for factory workers and townspeople with enough gumption to manage their own financial institutions. In 1982, when savings and loans were going belly up and businesses were downsizing, the agency charged with overseeing credit unions liberalized regulations to allow a number of smaller groups, each with their own common bond of work or community, to come together under one umbrella.

The banks immediately cried foul and have been crying ever since. Credit unions, they said, weren’t cute little mom-and-pop saving and lending shops, but large conglomerates using their tax-exempt status to get a free ride.

The credit unions responded that, while the institution itself is not taxed because there are no profits, the individual members pay taxes on the generally higher interest their deposits earn, and, if the union does well, annual dividends as well.

But those arguments are irrelevant to all but those in the finance industry. What matters to the average wage earner, to the retiree, to the young couple just starting out is high interest on deposits, low interest on loans and credit when its needed. If credit unions can meet those demands better than banks, good for the credit unions.

Congress can fix this archaic, 64-year-old law by passing H.R. 1151, the Credit Union Membership Act, which amends that creaky law to allow more than one group in a credit union, as long as each group has its own common bond. That is, it brings the law into conformity with the regulation. The bipartisan bill had 132 co-sponsors in the House as of Tuesday, 25 more signed on after the Supreme Court ruling Wednesday. Another 104 representatives need to sign on for passage, including Maine’s Tom Allen and John Baldacci, and they should. Let the banks and the credit unions squabble all they want. Better still, let them try to outcompete each other. Above all, let the public decide for itself what to do with its money.