E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Beyond their legitimate powers. Said of a company when exceeding the licence given to it by Act of Parliament. Thus if a company, which had obtained an Act of Parliament to construct a railway from London to Nottingham were to carry its rails to York, it would be acting ultra vires. If the Bank of England were to set up a mint on their premises, it would be acting ultra vires.