A more thorough explanation:

The prior-use doctrine is a principle that states that a government agency cannot take over property that is already being used for a public purpose without proper authorization from the legislature.

For example, if a park has been established and is being used by the public for recreational purposes, the government cannot take over the land to build a new government building without proper authorization.

Another example could be a road that has been built and is being used by the public for transportation. The government cannot take over the road to build a new highway without proper authorization.

These examples illustrate the prior-use doctrine because they show that the government cannot take over property that is already being used for a public purpose without proper authorization. This principle helps to protect the rights of individuals and communities who have invested time and resources into creating public spaces and infrastructure.