"No person shall … be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use without just compensation" (Constitution of the United States, Fifth Article of Amendment). The legal definition of "public use" can be very broad. For example, the Pennsylvania Code allows public utility companies to use eminent domain and to delegate the taking to pipeline operators. That means that, under Commonwealth law, a private company can exercise an immense government power!
Anytime you are faced with a "taking" under eminent domain, you need an experienced lawye