4.6.1. The Federal Rule: Before and After Methodology.The before and after method of valuation for partial acquisitions is accepted in all federal courts.724 It is often called the federal rule, although it also applies in many (but not all) state jurisdictions.725 A before and after valuation requires careful determination of the larger parcel (or parent tract) at issue— which may differ before and after the acquisition—and proper consideration of damages and benefits to the remainder property due to the government acquisition. Each of these issues will be addressed below, along with limited exceptions to the before and after method. 

The before and after method is “particularly advantageous” where the remainder may have been damaged and/or benefitted by the government’s acquisition.726 As recognized by the federal courts, proper application of the before and after method will result in a figure that reflects the value of the land actually acquired as well as any compensable damages and direct and special benefits to the remainder property.727 “All of the elements of value entering into just compensation”—i.e., the part acquired, compensable damage to the remainder and compensable benefit to the remainder—“are contained in the federal formula.”728 153