[smsm42]

> payment was made in that currency then repayment is expected in that currency.

The term you are looking for is "legal tender". That's the thing that has the property that if you pay your debt with it, the debt is considered settled. US$ is legal tender, but ETH is not. Of course, one could try to sue for fraud and lost profits and stuff, and may even win if by some weird chance the contract specified refunds in ETH, but then good luck collecting on that judgement. More likely, contract didn't, and then tough luck.

[oxide]

Well said. Legal tender is the difference here, USD comparisons are apples and oranges IMO.

as ETH is a volatile cryptocurrency and not US legal tender at all, while USD is the exact opposite: a fiat currency considered legal tender not only in the US but worldwide.

[fyi1183]

Legal tender has a specific legal meaning. I can assure you that the USD is not legal tender almost everywhere in the world.