Capital punishment – the process of sentencing convicted offenders to death for the most serious crimes and carrying out that sentence, as ordered by a legal system – first appeared in New Zealand in a codified form when New Zealand became a British colony in 1840. It was first carried out with a public hanging in Victoria Street, Auckland in 1842, while the last execution occurred in 1957 at Mount Eden Prison, also in Auckland. In total, 85 people have been lawfully executed in New Zealand.

Treason is the crime of attacking a state authority to which one owes allegiance. This typically includes acts such as participating in a war against one's native country, attempting to overthrow its government, spying on its military, its diplomats, or its secret services for a hostile and foreign power, or attempting to kill its head of state. A person who commits treason is known in law as a traitor.