Wis. Stat. § 631.43
1995 Wisconsin Act 21, which became effective on July 15, 1995, made significant changes in the law regarding the "stacking" of insurance policy coverage.
A clause providing that any amount payable under the insurer's policy would be reduced by monies paid by other insurance company's uninsured motorist coverage was not valid; therefore, the plaintiff was entitled to the entire benefits under both uninsured motorist provisions. Landvatter v. Globe Security Insurance Co., 100 Wis. 2d 21, 300 N.W.2d 875 (Ct. App. 1980). An insurance policy provision that prohibits the stacking of uninsured motorist benefits against the same insurer is prohibited by sub. (1). Tahtinen v. MSI Insurance Co., 122 Wis. 2d 158, 361 N.W.2d 673 (1985). Sub. (1) only prohibits the use of reducing clauses in indemnity coverages, not in underinsured motorist coverage. Kuehn v. Safeco Insurance Co. of America, 140 Wis. 2d 620, 412 N.W.2d 126 (Ct. App. 1987). If a single insurance contract incorporates coverage for two vehicles, charging two separate premiums, two policies have been issued under this section. Krause v. Mass. Bay Insurance Co., 161 Wis. 2d 711, 468 N.W.2d 755 (Ct. App. 1991). A fleet policy listing individual vehicles and assessing separate premiums for each is a separate policy for each vehicle and a single limit provision contained in the policy violates sub. (1). Carrington v. St. Paul Fire & Marine Insurance, 169 Wis. 2d 211, 485 N.W.2d 267 (1992). Carrington is extended to underinsured motorist coverage. An insured who pays separate premiums for each vehicle under a single policy can stack underinsured motorist coverage even though the policy contains a limit of liability clause. West Bend Mutual Insurance Co. v. Playman, 171 Wis. 2d 37, 489 N.W.2d 915 (1992). Although a policy's limit of liability language has been held invalid under this section for the purpose of preventing stacking, it is still valid for determining each policy's limit of liability. Schaefer v. General Cas. Co., 175 Wis. 2d 80, 498 N.W.2d 859 (Ct. App. 1993). The lack of underinsured motorist coverage on an accident vehicle was irrelevant when the insured had the coverage on two other vehicles. Under sub. (1), a policy definition amounting to a "drive-other-car" exclusion is invalid. Rodey v. Stoner, 180 Wis. 2d 309, 509 N.W.2d 316 (Ct. App. 1993), Patraw v. American Family Mut. Ins. Co., 185 Wis. 2d 757, 519 N.W.2d 643 (Ct. App. 1994). Liability coverages insuring against the risk of loss arising out of specified, owned vehicles do not insure against the same loss and thus sub. (1) does not apply to those coverages. Weimer v. Country Mutual Insurance Co., 211 Wis. 2d 848, 565 N.W.2d 595 (Ct. App. 1997), 96-1440. The applicability of sub. (1) cannot be ascertained by resorting to historical definitions of indemnity and liability insurance. An analysis must be made of whether a particular policy promises to indemnify the insured against the same loss as another policy. Taylor v. Greatway Insurance Co., 2000 WI App 64, 233 Wis. 2d 703, 608 N.W.2d 722, 99-1329. Sub. (1) did not invalidate a provision excluding coverage for a vehicle not owned by the driver but made regularly available to him when the owner's policy insured against losses arising from the use of the vehicle. The policies did not insure against the "same loss" within the meaning of sub. (1). Martin v. American Family Mutual Insurance Co., 2002 WI 40, 252 Wis. 2d 103, 643 N.W.2d 452, 00-2344. Section 632.05(2), the valued policy law, does not provide that an insured is entitled to the limits of all policies insuring a dwelling. Instead, sub. (1), the pro rata statute, specifically governs situations when two or more policies indemnify against the same loss. Absent the consent of the insurers, insureds are entitled to the full amount of their loss but not to the full amount of both policies if the combined limits exceed the actual loss. Wegner v. West Bend Mutual Insurance Co., 2007 WI App 18, 298 Wis. 2d 420, 728 N.W.2d 30, 05-3193. Sub. (1) refers specifically to "other insurance" provisions. The accepted meaning of other insurance" provisions does not include application to successive insurance policies. Other insurance" refers only to two or more policies insuring the same risk, and the same interest, for the benefit of the same person, during the same period. The issue here was not which of two or more policies pays first, because they were not concurrent policies between competing insurers that applied to the same time period, but successive policies from the same insurer. Plastics Engineering Co. v. Liberty Mutual Insurance Co., 2009 WI 13, 315 Wis. 2d 556, 759 N.W.2d 613, 08-0333. Stacking uninsured motorist coverage. Hannula. WBB Oct. 1985.