She thinks they are likely to be unfair:
... if the United States decides to apply a carbon tariff, then it must decide how much carbon it gets to produce compared with other countries. The Boxer-Lieberman-Warner bill, for example, determines whether another country's environmental regulation is comparable to the US (and thus exempt from a carbon tariff).
The bill establishes a dividing principle that freezes everyone at their current share of greenhouse-gas emissions and requires that countries reduce emissions from these levels. Under this standard, the US, which represents less than 5 percent of the world's population, is allocated over 18 percent of the world's greenhouse-gas production.
The problem for the planet's atmosphere is that other countries can do the same thing but based on different dividing principles. China could apply carbon tariffs to any country that has a higher per capita level of greenhouse-gas emissions than it does. (This would include the US, Canada, and the European Union.) India could adopt a formula that gives nations that have already contributed significantly to the current stock of greenhouse gases fewer emissions rights in the future.
This series of conflicting national level environmental measures is bad for the environment and bad for the global economy. ...