城堡准则（英语：castle doctrine，又译为堡垒原则），亦称城堡法（castle law）或居所防御法（defense of habitation law），一种法律原则，始于罗马法，存在于英美法中，赋予在特定情况下，被侵犯人可以对于入侵其宅邸（在某些州，也可以是机动车或工作场所等合法占用的空间）的进犯者使用武力（甚至是致命武力）进行防范和对抗的权力，而对于所造成的后果免于法律责任且不被起诉。

在西方文明里，宅邸非暴力性的法律概念始于罗马共和国。城堡准则这个词来源于历史上英国广泛认同的法理“英国人的家是他的城堡”。17世纪法律学者爱德华-科克爵士在他1628年的《英国法律学会》中确立了这个英国法律概念：

A castle doctrine (also known as a castle law or a defense of habitation law) is a legal doctrine that designates a person's abode (or, in some countries or states, any legally occupied place – e.g., a vehicle or workplace) as a place in which that person has certain protections and immunities permitting him or her, in certain circumstances, to use force (up to and including deadly force) to defend himself or herself against an intruder, free from legal responsibility/prosecution for the consequences of the force used. The term is most commonly used in the United States, though many other countries invoke comparable principles in their laws.