concurring.
I join the judgment of the court and am also pleased to join the essential reasoning of the majority’s thoughtful and comprehensive opinion. I write separately only to emphasize that I do not understand the majority’s rather expansive treatment of the prejudgment interest issue as constitut*439ing a departure from the settled law of the circuit that “the decision to award prejudgment interest rests in the sound discretion of the adjudicatory tribunal and involves a balancing of the equities between the parties under the circumstances of the particular case.” Myron v. Chicoine, 678 F.2d 727, 734 (7th Cir.1982). In exercising that discretion, the district court must give its prime attention to the intent of Congress in enacting the substantive statutory provision at issue. Therefore, prejudgment interest usually will be “necessary to carry out the federal policies of compensation and deterrence.” Williamson v. Handy Button Mach. Co., 817 F.2d 1290, 1297 (7th Cir.1987). On the other hand, “ ‘[ordinary’ does not imply inevitable,” id., and, as the Supreme Court pointed out in General Motors Corp. v. Devex Corp., 461 U.S. 648, 656-57, 103 S.Ct. 2058, 2062-63, 76 L.Ed.2d 211 (1983), prejudgment interest might be inappropriate at some times. See also Osterneck v. Ernst & Whinney, — U.S. -, 109 S.Ct. 987, 991 & n. 2, 103 L.Ed.2d 146 (1989) (noting that, in a federal securities action, a district court will consider a number of factors in determining the appropriateness of prejudgment interest). As our court pointed out in Williamson, “[substantial, unexplained delay in filing suit might be ... a reason [making prejudgment interest inappropriate], because delay shifts the investment risk to the defendant, allowing the plaintiff to recover interest without bearing the corresponding risk.” Williamson, 817 F.2d at 1298. A jury verdict that already compensates the plaintiff for the lost time value of money would also be an appropriate exception. Id.
The majority “suggests],” ante at 436-437, that district courts use the prime rate for fixing prejudgment interest where there is no statutory interest rate. Use of the prime interest rate, at least as a starting point, is a sensible approach. “Courts have increasingly looked to the prevailing interest rate ... as [an] indicator of just compensation.” Central Rivers Towing, Inc. v. City of Beardstown, 750 F.2d 565, 574 (7th Cir.1985). However, in this matter as well, we have recognized that the determination is “within the trial court’s discretion.” Id.; see also United States v. Peavey Barge Line, 748 F.2d 395, 402 (7th Cir.1984).
In short, today’s decision sets forth useful guidelines to assist the district court in the exercise of its discretion on the matter of prejudgment interest. As the majority also emphasizes, see ante at 437, I trust that today’s guidelines will not become a rigid litmus test when a district court determines that fulfillment of the congressional intent requires another approach. In such an instance, we have a right, of course, to expect that the district court will provide us with reasoned elaboration for its departure in order that our review may be meaningful.
The majority also addresses the adequacy of the measure of postjudgment interest provided by 28 U.S.C. § 1961. This congressional determination is not at issue in this case. Accordingly, I respectfully decline to express a view on this matter.