If diplomacy had worked, the cross-border pollution of Lake Roosevelt by a Canadian smelter operator wouldn’t have blown up into an international incident. But since responsibility was met with inaction, Teck Cominco finds itself in an unusual legal bind.

On Monday, the U.S. Supreme Court declined to hear the company’s appeal of lower court rulings that it must deal with the effects of nearly 100 years of dumping of waste that contained metals such as lead, zinc, mercury and arsenic. An estimated 20 million tons of slag was carried across the border near Trail, B. C., and was deposited in the lake and along its shores.

In 2003, the U.S. Environmental Protection Agency approached the company about studying the effects of the pollution, but little happened. So, two members of the Colville Confederated Tribes filed a lawsuit to force compliance with EPA rules. Soon after, the state of Washington threw its support behind the tribe.

While it’s easy to ascribe blame for the pollution, legal action involving three sovereign entities – Canada, the United States and the tribe – is extremely complicated. On our side of the border, the overwhelming sentiment is for Teck Cominco to clean up its mess. On the Canadian side, legal commentators are stunned that a Canadian company cannot fight back in Canadian courts.

Jacquie McNish of the Toronto Globe and Mail wrote, “The Supreme Court of the United States dealt a serious blow to the diplomatic tradition on Monday when it refused to hear Teck’s appeal.”

Traditionally, diplomacy has been the way to rectify cross-border disputes, whether they involved mining pollution, acid rain, dams, diminished fish stocks or many other controversies. Indeed, diplomacy resulted in Teck Cominco installing air pollution filters when it was determined that emissions were destroying apple crops in Washington state.

However, the company has only itself to blame for its slow response to the EPA after being approached in 2003. Three years later, Teck finally agreed to a $20 million study, but that was two years after the tribe filed its lawsuit.

Now that the lower court rulings have been effectively affirmed, it would seem to be a simple matter of enforcement. But such an action could trigger an avalanche of cross-border lawsuits, and U.S. companies could be hauled into Canadian courts. Such a mess would unravel decades of cooperation in jurisdictional matters. Only diplomacy can head off these tit-for-tat lawsuits.

Teck’s pollution study, under the watchful eye of the EPA, is set to wrap up in 2011. That’s a long time to wait, but solid science is needed before remedies can be considered. The best answer for all parties is for Teck to accept responsibility once all the data are in. Just as it did when it was damaging apples.

We understand the frustration of the tribe, but if enforcement springs from a court order, the cross-border legal battles will never end.