Prior use doctrine refers to a principle that a government agency may not appropriate property already devoted to a public use without legislative authorization. Property devoted to a public use cannot be taken and appropriated to another or different public use unless the authority to do so has been expressly given by the legislature or may be necessarily implied. In short, the power of condemnation may not be exercised where the proposed use will destroy an existing public use in the absence of specific legislative authority. However, when a taking will not materially impair or interfere with or is not inconsistent with the existing use, and the proposed use is not detrimental to the public, the court has authority to order a taking of the property.
The prior use doctrine applies to land held to accommodate reasonably foreseeable future demands although a mere naked possibility that it will be so used will not immunize it from condemnation under a general power. The test to protect the property from condemnation under the prior use doctrine is not absolute certainty that it will be used for that purpose in the future. The test must be whether there is a reasonable assurance that the intended use will come to pass. [New Haven v. East Haven, 35 Conn. Supp. 157 (Conn. Super. Ct. 1977)]