One virtue of the Supreme Court's lamentable January 21 decision striking down all restrictions on corporate (and, by implication, union) independent spending in federal election campaigns is that Congress might be able to fix the biggest problem that the five conservative justices created.

Contrary to many a liberal critique, that problem is not that additional corporate and union cash will pour into campaigns and send the political corruption quotient soaring. It is that few stockholders (or union members) have consented to such corporate or union spending of their money.

And the most logical, politically viable, and constitutionally defensible solution would be a law requiring such consent.

The justices would likely -- and justifiably -- strike down any congressional response designed simply to keep as much corporate cash out of politics as possible, such as banning campaign spending by federal contractors. The Court has held for more than 30 years that independent spending on campaigns is protected speech that cannot be restricted either in the name of minimizing corruption or to limit the political clout of rich people. That's why Citizens United v. Federal Election Commission was correct as applied to nonprofit ideological corporations whose very purpose is to advance political causes and candidates.

A for-profit corporation is different. Investing in its stock in no way signals consent for the company to spend that money attacking political candidates whom many of its stockholders support, or endorsing candidates whom many oppose.