No basis to sue here: you are perfectly allowed to lend money without interest, you just have to pay gift taxes on it. (If it is really a loan, the gift taxes o

No basis to sue here: you are perfectly allowed to lend money without interest, you just have to pay gift taxes on it. (If it is really a loan, the gift taxes only apply to the forgone interest. But, keep in mind that if they can’t repay it, they will owe income taxes on the whole amount!)