Courtesy of the Washington Monthly, which asked if the "loophole" of using a $1 trillion platinum coin to avoid a debt limit problem was legally permissible, Tribe answered as follows:
"I don’t think it makes sense to think about this as some sort of 'loophole' issue. Using the statute this way doesn’t entail exploiting a loophole; it entails just reading the plain language that Congress used. The statute clearly does authorize the issuance of trillion-dollar coins. First, the statute itself doesn’t set any limit on coin value. Second, other clauses of 31 USC §5112 do set such limits, but §5112(k)—dealing with platinum coins—does not. So expressio unius strengthens the inference that there isn’t any limit here.
"Of course, Congress probably didn’t have trillion-dollar coins in mind, but there’s no textual or other legal basis for importing this probable intention into the statute. What 535 people might have had in their collective 'mind' just can’t control the meaning of a law this clear.
"It’s also quite clear that the minting of such a coin couldn’t be challenged; I don’t see who would have standing.
"Bottom line: This is a situation where the political and economic considerations, not the legal considerations, have to drive the decision-making about this option. It’s certainly a lot better from just about every perspective than having the nation stuck on either horn of the very real dilemma you outlined below, which I agree offers no plausible way out as long as enough leaders in Congress insist on playing Russian Roulette with our economy and risking our full faith and credit by using the debt ceiling as a bargaining chip as they are threatening to do."