It’s a bit complicated but if you really want to know:
http://dealbook.nytimes.com/2014/02/25/argentina-takes-its-debt-case-to-the-u-s-supreme-court/?_php=true&_type=blogs&_r=0
Thank you. Holly smoke! I’m against courts, especially foreign courts (from Argentina’s view, but I’ll explain) in deciding sovereign issues.
The US is signatory to several treaties that tie our sovereignty to the decisions of foreign courts. For example, GWB put a tariff on steel to get votes from Pennsylvania. (BTW, this pissed me off as it doubled the price of steel I had to buy at the time.) We were taken to a foreign court and lost (almost a forgone conclusion). The treaty allowed our trading partners to put tariffs on anything they wanted to. The resulting financial impact forced Bush to rescind the tariff. This is also, most likely, how the UN arms treaty would be enforced.
It’s unlikely any foreign judge would ever find for the US. Therefore we should not set a precedent of our courts deciding to penalize other nations.
Further, I suspect there is no way to ever get out of these treaties, as that would be an issue decided in a foreign court. Our trade could be permanently destroyed.