In addition to the DSU Article 22 proceedings, the GATS Article XXI compensation issues and the U.S. legislative issues, there is now another aspect to the Gambling dispute: a constitutional challenge. According to the Seattle Post-Intelligencer, an attorney in Washington state, Lee Rousso, "sued the state of Washington in an effort to overturn its 2006 ban on Internet poker, ... [c]alling it a direct violation of the U.S. Constitution's commerce clause."
The article explains that the ban, which took effect last spring, "specifically prohibited the type of Internet-based card games such as Texas Hold 'Em that poker players in Washington -- Rousso among them -- have used to qualify for the annual [World Series of Poker]" and also notes that "[l]awmakers said it was an effort to put the state in compliance with the Interstate Wire Act" (one of the measures at issue in the WTO dispute).
Interestingly, there seems to be some overlap between the kinds of issues raised here and those in the WTO dispute. In his complaint, Rousso argued that "the state measure was passed not to put the state in compliance with the federal wire act -- something it does not do anyway, he said -- but instead to protect the in-state gambling industry, including card rooms and casinos." This, he said, "puts Washington in clear conflict with the Constitution's commerce clause, which forbids individual states from passing protectionist laws against other states' business."