The TPNW reinforces earlier treaties relating to nuclear weapons, including the Non-Proliferation Treaty of 1968, which aims to limit the number of nations possessing nuclear weapons and advance the goal of disarmament.

As affirmed by the International Court of Justice in 1996, nations have a legal obligation “to pursue in good faith and bring to a conclusion negotiations leading to nuclear disarmament”. The lack of progress towards this end was a major motivation for the negotiation of the TPNW.

Other complementary treaties include the Comprehensive Nuclear-Test-Ban Treaty of 1996 and regional treaties establishing nuclear-weapon-free zones in Latin America and the Caribbean, the South Pacific, Africa, Southeast Asia and Central Asia.

The TPNW is based on a body of law known as international humanitarian law, which limits the methods and means of warfare. Parties to an armed conflict must refrain from using weapons incapable of distinguishing between civilians and combatants, or those that inflict superfluous injury or unnecessary suffering.