Ultra vires (Latin: "beyond the powers") is a Latin phrase used in law to describe an act which requires legal authority but is done without it. The constitutional theory of judicial review has long been dominated by the doctrine of ultra vires, under which a decision of a public authority can only be set aside if it exceeds the powers granted to it by Parliament. The role of the courts was seen as enforcing the "will of Parliament" in accordance with the doctrine of Parliamentary sovereignty.
The HS2 Compensation Case
This 2013 example remains a good example of the use of JR to hold the government to account, when the Official Opposition had been unable to. In this case, the pressure group 51m and 4 other groups acted on behalf of people whose homes are along the proposed High Speed 2 rail link from London to Birmingham, and brought 10 cases for review at the High Court. They argued, amongst other issues, that the government had failed to properly take into account environmental considerations of the impact of building HS2 and that the government had not adequately considered the compensation scheme for those whose property would be within 0.6miles of the line. Whilst the government won 9 of the 10 cases brought, they lost the compensation argument, with the judge concluding that “the consultation on compensation was so unfair as to be unlawful", requiring the government to revisit its plans.