Template:M summ 2002 ISDA 13(d)

Don’t confuse sovereign immunity with ultra vires — cue thunder crack at the mention of Orange County or Hammersmith and Fulham council and a dramatic look from our house gopher — for they are quite different things.

• Ultra vires: If a contract is beyond your powers or capacity to enter into a contract in the first place then it is void ab initio; any payments you have made under that contract are also void and you may reclaim them, and you can appeal to the court system to do that. That is to say, ultra vires is an “intra-legal” measure, recognised, defended and enforced by the courts.
• Sovereign immunity: Sovereign immunity is a different, “extra-legal” thing: it is to say “I am, quite literally, above the law: I am the law, and I do not have to subject myself to the judicial branch of my law — or anyone else’s law — unless I choose to.” This extends to being free from judicial intervention if I decide not to perform my contractual obligations, but it also means I cannot myself resort to the court process to make my counterparty perform its obligations. If I choose to go to court, then I subject myself fully to the courts as regards actions my counterparty wishes to bring against me.