4.1.4. Defining Property Interests. An appraiser cannot develop an opinion of market value for just compensation purposes without knowing what, exactly, the United States will acquire.187 A legal description identifies a property’s precise physical or geographic location. The property interest or interests to be acquired must be described with equal precision. The nature and extent of any property interest being acquired is determined by the acquiring agency, as delegated by Congress—not the appraiser, the landowner, or the courts.188 Under federal title regulations, the property interest must be sufficient for the government’s purpose in acquiring it,189 balanced against “the Government’s natural desire and duty to deplete the public purse no further than necessary in carrying out its projects”190 and other considerations that may be imposed by specific statutes and regulations. “Of course, payment need only be made for what is taken, but for all that the Government takes it must pay.”191 It is therefore critical for the agency to carefully and precisely define the property interest(s) being acquired and expressly state what interest(s), if any, will remain with the landowner.192 

Agencies are well advised to follow the maxim “measure twice, cut once” in defining the property interests to be acquired. An opinion of market value can only be used for just compensation purposes if it reflects the market value of the precise property interest being acquired.193 If an appraiser is provided an incorrect or outdated property interest, the resulting opinion of market value—no matter how well supported—will be of little or no use for purposes of just compensation.194 Moreover, in condemnation, agencies must stand by and pay compensation for the stated terms of the property interest taken.195 If those terms are not carefully defined, a condemning authority may well “‘discover[ ] that the judgment it won gave it more of a title than it wanted to pay for,’ but it must pay for what it won nonetheless.”196 92