It's a painful coincidence that Hurricane Katrina swept through the Gulf Coast, disrupting oil supplies and driving up spot prices, precisely as Hawai'i prepares to launch a unique gasoline price "cap" law tied in part to those very Gulf Coast oil prices.

The likely result will be that permitted prices for local wholesale gasoline will go up, not down, under the new law.

The cap is not a mandate to sell at maximum prices. But wholesalers are likely to go for maximum prices when oil is high, surmising that their margins will be depressed under the cap if and when wholesale prices fall.

The law, in theory, is designed to give Hawai'i's gas consumers the same experience as those in most other states: When wholesale prices go up, pump prices go up; when wholesale prices decline, so do retail prices.

Historically, that's not been the case in Hawai'i. And until recently, Hawai'i usually had the highest gas prices in the nation.

Indeed, there are several explanations offered for that, including the fact that we are a stable, relatively non-elastic isolated spot market. And gasoline refiners have tended to charge what the market will bear. In Hawai'i, apparently, it will bear a lot.

Lawmakers concluded that capping prices relative to what happens elsewhere makes the most sense.

Gov. Linda Lingle essentially held her nose and allowed the latest version of the plan to become law, even as she argued that it would likely create shortages and drive up prices.

By allowing it to become law, Lingle said she avoided having to deal with an earlier version that was even worse. And she thought the delayed implementation date would give legislators time to rethink the matter or look into her alternatives. That was not to be. So tomorrow, the gas-cap law takes effect.

Lingle promises she'll give this effort her best shot, despite her misgivings. Her administration will ensure that the law will be implemented as sensibly and as close to what legislators wanted as possible.

Lingle is equally clear that she will not casually use her power to suspend the law if serious disruptions do occur, as she fears. Rather, she will wait until there is hard evidence that the law is causing serious harm to supplies or public health, welfare and order.

At this point, Lingle's approach is the only real option we have.

These are uncharted waters — Hawai'i is the only U.S. state to impose a gas cap. Much will depend on the goodwill and fair practices of the refiners, the middlemen and the retailers.

A lot also rests on consumers, who can cause problems and disruptions by panicking and hoarding.

There is plenty of gasoline for Hawai'i. It is critical that consumers take a calm and relatively long-term view. Topping off every car in the household is not necessary.

It's time to give the gas cap a fair, honest shot. If it works — and even Lingle says she would be pleased if it somehow does — consumers benefit.

If it doesn't, then it can be suspended and policymakers can go back to the drawing board on this complicated matter.