As another toxic political season gasps to a close, it would seem an odd time to champion campaign spending.

Well, “champion” is an overstatement. “Tolerate” is closer to the mark. But the underlying concern is that when free expression is at its most odious, that’s the time it requires a defense.

The Washington state Supreme Court last week held that a rule governing how much money some lab or business organizations can donate to candidates is not restrictive enough. Under that 10-year-old rule, local chapters of state or national unions and trade associations could contribute separately to political campaigns up to the full $1,350 allowed by law — as long as their parent organizations stayed on the sidelines.

Barring a reconsideration of the ruling — which the state is entitled to request — that will change for future elections.

The Supreme Court ruled on Thursday that the various local elements of the same umbrella organization are governed by a collective limit on contributions. Their giving can add up to a total of $1,350; they can’t give that much separately.

This, of course, means certain campaigns will have less money with which to produce and broadcast, mail or publish those nasty attack ads that have flooded the environment even more than usual this year.

Good riddance? Arguably.

But the price for it is a restriction on the ability of citizens to use their resources to advocate for candidates and causes they favor. The precedent should give us pause.

If anything, the disturbing levels to which negative political discourse (a charitable word for it) has risen is evidence that years of campaign finance reform efforts have failed to achieve improvement. The “Willie Horton” strategy that helped torpedo Michael Dukakis in 1988 is almost tame by the standards of 2004.

Expenditure and contribution limits being demonstrably ineffective, there is a more desirable safeguard.

All of us, as voters and citizens, need to use our heads. We need to recognize that political advertising is deceptive, consisting mostly of spin and distortion. We need to check out claims before embracing them. We need to find and rely on respected and independent sources of information in making decisions.

We recommend — again — an impartial Web site operated by the Annenberg Public Policy Center of the University of Pennsylvania: www.factcheck.org. The Washington Public Disclosure Commission ( www.pdc.wa.gov) lists detailed information about who is contributing to which campaigns and causes.

Disclosure and discernment are more effective checks on underhanded campaigning than finance limits ever will be.