In a quiet office in the Faculty of Law's Flavelle Building, Jutta Brunnée is answering some tough questions: When, if ever, is it appropriate to militarily intervene in other nations? How do sovereign states address global environmental problems?

A professor of international law and international environmental law, Brunnée has spent her career examining how these laws shape the behaviour of nations. Their challenge, she says, is tackling "collective problems in a world of sovereign states."

Brunnée became interested in the environmental side of international law during the field's early stages. "Twenty years ago, there were some basic principles, and a handful of treaties acknowledging that yes, we have international environmental problems that need addressing."

Today, international environmental law is a highly specialized area with hundreds of agreements addressing everything from ozone depletion and water pollution to endangered species. In her role as the Metcalf Chair in Environmental Law, Brunnée is filling the need for an authoritative voice on the field as co-editor of the upcoming Oxford Handbook of International Environmental Law. The book outlines theoretical concepts and captures how not only states, but international organizations, NGOs and industry, are involved in shaping and implementing environmental law.

Climate change, says Brunnée, is one area where these various players are involved in negotiations. She combined theory with practice in 1998, when she spent a year as a legal advisor on the Canadian Delegation to the United Nations Framework Convention on Climate Change. "It's not as simple as saying that Canada commits to reducing emissions. For an agreement to be successful, countries need to find ways to change the behaviour not just of industry, but across all segments of society."

Challenging current paradigms is inherent in Brunnée's approach to her scholarship. As an international law scholar, she also examines the use of force between states and the role of the UN since 9/11. Under international law, military intervention is permissible only on the grounds of self-defense or Security Council authorization. Brunnée has been grappling with the question, "Is military intervention on humanitarian grounds ever appropriate?"

A recent Canadian initiative called The Responsibility to Protect promotes the idea that sovereign states have a responsibility to protect their own citizens from avoidable catastrophe. When they are unwilling or unable to do so, this responsibility must be shared by a broader community of nations. "The report embraces an important conceptual shift because it's not about the right to intervene, but about the responsibility to protect human lives." Brunnée, whose comments on the report are featured on the Foreign Affairs website*, says the challenge is to strike a balance between constraining military intervention and the need to actually enable it where urgently required.

While her research finds resonance in seemingly disparate topics, Brunnée says she's driven by what international law and international environmental law have in common. "Neither is going to prevent states that want to breach laws from doing so. But what they can do is force key actors to continually justify their actions against shared standards. The hard work of international law is to build and rebuild shared norms."

- Maria Saros Leung

What do forest fires and bank machine customers have in common? Seemingly nothing, until you talk with David Martell, a professor in U of T's Faculty of Forestry and a leader in research into how to manage forest fires and the resources used to fight them.

Over the past 30 years, Martell and his graduate students have developed important new insights into the perplexing problem of how to deal with fires that can grow to more than 50,000 hectares (about 125,000 acres).

As expert as he is, Martell's roots are not in forests, but industrial engineering. A native of Kirkland Lake in northeastern Ontario, he has childhood memories of "seeing forests that had been burned, but I never thought that forestry could be a career."

But a couple of things happened during his undergraduate years at U of T that spawned what would become his life's work. "I studied operations research and learned how to develop mathematical models that can be used to model human-managed systems, such as bank machines." A key component of that was queueing theory - the science of dealing with congestion when designing facilities that serve customers.

He took a summer job working with the then Ontario Department of Lands and Forests, helping build a simulation model of the use of airtankers in fighting forest fires.

The knowledge of queueing theory was (and still is) essential to the job. And 30 years later, Martell is still working on similar problems. Much of his research is used regularly by forest fire managers today.

"Bank machines are a perfect example of queueing systems," he says. "When the bank decides how much to invest in the machines to serve customers it has to balance the cost of the machines with the risk of annoying customers with long lineups."

The same theory can be applied to deploying resources to forest fires.

The fire becomes the "customer." The "servers" are the resources used to control the fire - airtankers, helicopters and fire fighters. The longer fires "wait," the more "annoyed" (and damaging) they become. "Airtankers cost roughly $30 million each. They are an expensive but crucial part of the operation. So the government has to figure out how it can balance airtanker costs with response time. I develop queueing models that can be used to help determine an optimal number of airtankers."

While he has had success in designing effective service models using queueing theory, it remains a tricky problem because fires are unpredictable. "The number of customers that use bank machines is relatively stable. With forest fires, every day is different. So we have to develop models that are flexible enough to deal with variation in the number of fires, the weather and the location."

Martell notes that the forest fire research community has built a productive relationship with fire management agencies and huge progress has been made. "This is a very complex, computationally intractable problem we can never really solve. The challenge is to keep getting better, which we are. We just keep banging away to improve our models."

- Paul Fraumeni