Capacity and authority
The twin pillars of paranoia that remain when all is said and done on your negotiation and you're ready to sign on the dotted line.
- whether the fellow who purports to sign for your counterparty has any grounds to do so is a question of his authority
- whether your counterparty is constitutionally able to enter into obligations of the type contemplated by your contract, is a question of its capacity (as to which see also ultra vires.