In legal terms, something that's intra vires is officially allowed, like when a company buyer makes an intra vires purchase, filling out all the appropriate forms first.
The Latin phrase intra vires means "inside the powers," and it's often used to contrast something that's ultra vires, "outside the powers." Legally, an ultra vires action is anything that someone's not authorized to do (imagine you decided to fire a co-worker, despite not being his supervisor), as opposed to an intra vires action: "The judge has the power to make that ruling, so it was an intra vires decision."