Extraterritorial jurisdiction or ETJ is the legal ability of a government to exercise authority beyond its normal boundaries.

In the U.S., many states have laws or even constitutions which permit cities to make certain decisions about the land beyond the town's incorporated limits. Texas, Alaska, and North Carolina are all examples of states which allow cities to claim ETJ over zoning laws, which is the most common use of ETJ. In California, ETJ is referred to as a city's "Sphere of Influence". Some examples include Los Angeles which has a sphere of influence over the unincorporated islands of census designated places in and around its boundaries, and Palmdale which has a large sphere of influence on its unincorporated suburbs as well as the cities within its U.S. government designated Foreign Trade Zone . Some states even require that ETJ be established over an area for an extended time period (usually one year) before it can be subject to annexation. Most set the ETJ distance based upon a city's population.

Extraterritorial jurisdiction can also apply internationally. For example, the United States has status of forces agreements with many nations which give the United States jurisdiction over members of its military.