Smart v HMA was a Scottish criminal case decided by the High Court of Justiciary on appeal held that it is not a defence to a charge of assault that the injuries were caused in the course of a consensual fight. This is known as the 'Square Go' case, where those involved agreed to a 'square go' outside the pub where they were drinking.

The court held " “it is in the public interest that it should be decided and made known that consent to a 'square go' is not a defence to a charge of assault based on that agreed combat.”

The situation was different with indecent acts or injuries caused in the course of organised sports, such as boxing.

This case is reported at 1975 JC 30.