4.9. Inverse Takings.Most valuation assignments under these Standards involve intentional acquisitions, in which the United States purposely seeks to acquire property (by negotiated purchase, exchange, or eminent domain). But actions of the United States may also result in its taking property without intending to do so. In such a situation, called an inverse taking (or inverse condemnation), a landowner can sue the United States for compensation.1015 Inverse takings claims involve important legal and practical differences from other types of federal acquisitions.1016 

The most significant difference between an inverse taking claim and a direct condemnation or other affirmative acquisition is the threshold question of liability: In filing a direct condemnation, the United States expressly acknowledges the actual or proposed property acquisition and its obligation to pay compensation. In an inverse taking claim, on the other hand, the United States may contest the landowner’s claim that a taking occurred for which just compensation must be paid under the Fifth Amendment.1017 Accordingly, in an inverse taking claim, the court must first determine whether a taking occurred for which just compensation must be paid. If so, the case can then proceed to the compensation phase to determine what amount of compensation is due. Appraisers may be retained to develop opinions in connection with the liability phase, the compensation phase, or both. 

The liability inquiry will vary depending on the nature of the inverse taking claim. The issue is rather straightforward if the government’s action resulted in the government’s permanent physical occupation of the land in question.1018 But “[i]n view of the nearly infinite variety of ways in which government actions or regulations can affect property interests, the Court has recognized few invariable rules in this area.”1019 In regulatory takings claims, the federal courts have developed various tests to determine whether a taking has occurred: the character of the government action; the extent to which the regulation interferes with distinct, investment-backed expectations; and the economic impact of the regulation.1020 These distinct inquiries may alter the appropriate considerations (as well as the terminology) for determining the larger parcel for liability purposes in inverse takings claims, as discussed in Section 4.3.4.8. 

If the court finds that a compensable taking occurred, litigation will proceed to the compensation phase, in which the standard valuation rules apply. Generally, the appraiser will be asked to develop opinions of the market value of the affected property before and after the taking. As discussed in Section 4.2.1.1, the date of value is typically the date of taking, which should be provided by legal counsel. 185