Jury equity is a power that juries have in the British legal system. It is similar to what is known as "jury nullification" in the American system.
When a jury exercises this power, it refuses to convict a defendant even if it thinks that he or she is legally guilty. It does so because it believes that the law is unjust. By doing this, the jury is passing its own judgement on whether the law is equitable, not just whether the defendant is guilty under the law as it now stands. This is seen as a way for the people of a country to resist overreaching on the part of the government.