¶ 80. 9concurring in part and dissenting in part). I concur in and join the majority opinion's conclusion that the uninsured motorist policy in this case is unambiguous and does not provide coverage when the owner of the uninsured vehicle was not negligent. I also concur in and join the majority's conclusion that Wis. Stat. § 632.32(4)(a) does not mandate coverage under these circumstances.
¶ 81. However, I dissent from the majority's conclusion that a court of appeals decision loses all precedential value when it is overruled in part by this court.1 I dissent because this conclusion is unnecessary to the resolution of the merits of this case; it is made without identifying a problem requiring this change; and it is made without input from the many Wisconsin judges and lawyers who will be impacted by the court's decision.
*763I. BACKGROUND
¶ 82. Whether a court of appeals opinion that has been overruled on other grounds retains any precedential value for its other holdings has no relevance to the merits of this appeal. Rather, we address it because Chief Justice Abrahamson has long promoted a supreme court rule requiring that an overruled court of appeals decision becomes a nullity. See, e.g., State v. Gary M.B., 2004 WI 33, ¶ 44 n.1, 270 Wis. 2d 62, 676 N.W.2d 475 (Abrahamson, C.J., dissenting) ("My own view at this time is that when this court reviews a decision of the court of appeals, the court of appeals decision no longer has precedential value."); Bergmann v. McCaughtry, 211 Wis. 2d 1, 10 n.8, 564 N.W.2d 712 (1997).
¶ 83. Kevin Blum set the stage for this discussion when he argued that the court of appeals erred by employing reasoning from Hemerley v. American Family Mutual Insurance Co., 127 Wis. 2d 304, 379 N.W.2d 860 (Ct. App. 1985), which was overruled by Hull v. State Farm Mutual Automobile Insurance Co., 222 Wis. 2d 627, 586 N.W.2d 863 (1998). Blum's argument permitted the court to address its treatment of court of appeals opinions that are overruled in part.
II. DISCUSSION
¶ 84. Whether a court of appeals opinion that has been overruled in part retains any precedential value is a policy question for this court. However, no matter how this policy question is resolved, it will not affect the court's substantive decision in regard to Blum's claims.
¶ 85. The majority opinion begins its discussion recognizing that as a general rule, holdings of a court of appeals decision not specifically overruled by the Wis*764consin Supreme Court or the United States Supreme Court retain their precedential value.2 The majority cites to Sweeney v. General Casualty Co. of Wisconsin, 220 Wis. 2d 183, 192, 582 N.W.2d 735 (Ct. App. 1998) for this proposition. The majority opinion explains that the court of appeals "first described" this generalized rule in Spencer v. City of Brown, 215 Wis. 2d 641, 650-51, 573 N.W.2d 222 (Ct. App. 1997).3
¶ 86. Although it is true that the rule may have been first described by the court of appeals in Spencer, we cited court of appeals opinions for propositions of law that are not overruled before Spencer. See, e.g., State v. Williams, 148 Wis. 2d 852, 855, 436 N.W.2d 924 (Ct. App. 1989) (relying on Town of Two Rivers v. DNR, 105 Wis. 2d 721, 315 N.W.2d 378 (Ct. App. 1981), overruled on other grounds by Milwaukee Metro. Sewerage Dist. v. DNR, 126 Wis. 2d 63, 72, 375 N.W.2d 649 (1985)).
¶ 87. Both the Wisconsin Supreme Court and the court of appeals have cited to legal principles in court of appeals decisions that have been overruled in part. See, e.g., Folkman v. Quamme, 2003 WI 116, ¶ 64, 264 Wis. 2d 617, 665 N.W.2d 857 (citing Mills v. Wis. Mut. Ins. Co., 145 Wis. 2d 472, 427 N.W.2d 397 (Ct. App. 1988), overruled on other grounds by West Bend Mut. Ins. Co. v. Playman, 171 Wis. 2d 37, 489 N.W.2d 915 (1992); State v. Orta, 2000 WI 4, ¶ 23, 231 Wis. 2d 782, 604 N.W.2d 543 (citing State v. Friday, 140 Wis. 2d 701, 412 N.W.2d 540 (Ct. App. 1987), overruled on other grounds by State v. Friday, 147 Wis. 2d 359, 434 N.W.2d 85 (1989)); State v. Eugenio, 219 Wis. 2d 391, 412, 579 N.W.2d 642 (1998) (citing Wikrent v. Toys "R" Us, Inc., 179 Wis. 2d 297, 507 N.W.2d 130 (Ct. App. 1993), *765overruled on other grounds by Steinberg v. Jensen, 194 Wis. 2d 439, 534 N.W.2d 361 (1995)); C. Coakley Relocation Sys., Inc. v. City of Milwaukee, 2007 WI App 209, ¶ 16, 305 Wis. 2d 487, 740 N.W.2d 636 (citing City of Janesville v. CC Midwest, Inc., 2006 WI App 21, 289 Wis. 2d 453, 710 N.W.2d 713, overruled on other grounds by City of Janesville v. CC Midwest, Inc., 2007 WI 93, 302 Wis. 2d 599, 734 N.W.2d 428).
¶ 88. The citation rule in federal court is different than that proposed by the majority. In federal court, a "reversed" opinion can be cited for principles that were not reversed, but an opinion that has been "vacated" has no precedential authority. Durning v. Citibank, N.A., 950 F.2d 1419, 1424 n.2 (9th Cir. 1991) (citing O'Connor v. Donaldson, 422 U.S. 563, 578 n.12 (1975))." '[V]acating the judgment of the Court of Appeals deprives that court's opinion of precedential effect, leaving this Court's opinion and judgment as the sole law of the case.'" Id. (quoting O'Connor, 422 U.S. at 578 n.12); see also Newdow v. Congress of the United States of Am., 383 F. Supp. 2d 1229, 1240 (E.D. Cal. 2005); Charles A. Sullivan, On Vacation, 43 Hous. L. Rev. 1143, 1148 (Winter- 2006) (commenting that "a vacated opinion is not precedent in the sense that it binds anyone; but such opinions may remain persuasive," but "a decision reversed on other grounds is not merely persuasive but also binding").
¶ 89. The nomenclature by which an appellate court describes its action in regard to a decision it has reviewed is varied. A decision may be reversed, overruled or vacated, in its entirety or in part. Each of those terms has a different meaning. A decision is "reversed" in "[a]n appellate court's overturning of a lower court's decision." Black's Law Dictionary 1433 (9th ed. 2009). A decision is "overruled" when it is "set aside [as] prece*766dent[] by expressly deciding that it should no longer be controlling law." Id. at 1213. A decision is "vacated" in order "to nullify or cancel; make void; [or] invalidate" the decision. Id. at 1688. There may be good reasons to treat differently court of appeals decisions that are reversed, overruled and vacated; however, no one has explored this issue. Until there is further study, it would be cavalier to decide it.
¶ 90. Moreover, it remains uncertain how the majority's holding will impact the manner in which Wisconsin cases are classified on Westlaw and LexisNexis, the premiere online legal research services. Both research services use symbols to indicate how other case law has affected a particular opinion. The symbols indicate neutral, positive, cautionary or negative treatment. In Westlaw, a case that has been expressly overruled generally has a red flag and the statement, "No longer good for at least one point of law."4 However, when a case is reversed, rather than overruled, Westlaw shows the same red flag and cautionary statement.5
¶ 91. The majority opinion addresses only "overruled" court of appeals decisions. It does not prevent the use of legal principles from a decision that is "reversed."
¶ 92. Furthermore, whether a court of appeals decision loses all precedential value when it is overruled in part by this court was given little attention by the parties. On only five pages of Blum's brief, was the issue the majority takes up mentioned. There, Blum's argu*767ment focused on his contention that the court of appeals erred because it relied in part on Hemerley, citing Chief Justice Abrahamson's dissenting opinion in Gary M.B., 270 Wis. 2d 62, ¶ 44. The respondent, 1st Auto & Casualty Insurance Co., devoted less than one page of its brief to the issue. At oral argument, the court was unable to obtain further assistance from counsel.
¶ 93. And finally, neither the discussion of the appellant nor the respondent provided any background or context in which to place this issue. For example, neither party addressed how many times cases cited as "overruled on other grounds" have been used in subsequent cases; whether changing the rule would cause a hardship for lawyers or for trial and appellate judges who have relied on these cases for foundational legal principles; or whether some other rule might better serve the bench and the bar. However, notwithstanding the lack of information provided to the court on this complicated question, the majority pushes ahead.
III. CONCLUSION
¶ 94. In my view, a better approach would be to refer the issue to the judicial council, so that input can be obtained from the bench and the bar. It would also be useful to study how other states treat opinions that are overruled in part, as well as learning how the federal rule has operated throughout the 50 states.
¶ 95. Because I believe we have undertaken a new rule without adequate knowledge upon which to base our decision, I respectfully dissent from the portion of the majority's opinion that unnecessarily concludes that court of appeals decisions overruled by this court no longer retain any precedential value.
*768¶ 96. I am authorized to state that Justices ANNETTE KINGSLAND ZIEGLER and MICHAEL J. GABLEMAN join this concurrence/dissent.Majority op., ¶ 42.
Id., ¶ 44.
Id.
See, e.g., Hemerley v. Am. Family Mut. Ins. Co., 127 Wis. 2d 304, 379 N.W.2d 860 (Ct. App. 1985), overruled by Hull v. State Farm Mut. Auto. Ins. Co., 222 Wis. 2d 627, 632, 586 N.W.2d 863 (1998).
See, e.g., Hull v. State Farm Mut. Auto. Ins. Co., 215 Wis. 2d 323, 572 N.W.2d 902 (Table) (Ct. App 1997), rev'd, 222 Wis. 2d 627, 632, 586 N.W.2d 863 (1998).