When a general contractor or project owner tenders a claim under a subcontractor’s Commercial General Liability (CGL) policy for additional insured coverage, the insurer’s first basis for denying coverage is often to argue that the CG 20 10 endorsement covers only the additional insured’s vicarious liability for the named insured’s negligence, and that any independent fault on the additional insured’s part extinguishes coverage entirely. However, the endorsement’s text and the weight of judicial authority suggest otherwise. This article examines the “caused, in whole or in part, by” language that ISO has included in every edition of its CG 20 10 endorsement since July 2004, traces the key judicial decisions interpreting that language, and explains why a national consensus has develop that rejects the vicarious-liability-only limitation that insurers continue to press.
CG 20 10 is an Insurance Services Office (ISO) endorsement form entitled “Additional Insured – Owners, Lesssees or Contractors – Scheduled Person or Operation.” On construction projects, it is often included in a subcontractor’s CGL policy to add the project’s general contractor (or project owner or developer) as an Additional Insured under the subcontractor’s CGL policy. Several editions of CG 20 10 exist—the most current is CG 20 10 12 19—and each provides varying scopes of coverage.
Since ISO released the CG 20 10 07 04 edition in July 2004, the CG 20 10 endorsement has limited an additional insured’s coverage to:
. . . liability for ‘bodily injury’, ‘property damage’ or ‘personal and advertising injury’ caused, in whole or in part, by:
Your acts or omissions; or
The acts or omissions or those acting on your behalf;
1. Your acts or omissions; or
2. The acts or omissions or those acting on your behalf;
In the performance of your ongoing operations for the additional insured(s) at the location(s) designated above.[1]
Every subsequent edition, including the current CG 20 10 12 19 form, has carried the “caused, in whole or in part, by” language forward without substantive modification. The addition of the “caused, in whole or in part, by” language in 2004 was significant because, under prior editions of CG 20 10, coverage was afforded to additional insureds “only with respect to liability arising out of your ongoing operations performed for that insured.”[2] Courts across the country consistently construed the “arising out of” language to require only a minimal causal nexus between the named insured’s work and the additional insured’s liability, well short of proximate cause and without any requirement that the named insured be at fault. See Utica Nat’l Ins. Co. of Texas v Am. Indem. Co., 141 S.W.3d 198, 203 (Tex 2004); Manufacturers Cas. Ins. Co. v. Goodville Mut. Cas. Co., 403 Pa. 603, 607–08 (1961).
Replacing the “arising out of” language with the “caused, in whole or in part” language fundamentally changed coverage for additional insureds under CGL policies containing CG 20 10 by limiting the endorsement’s coverage to the additional insured’s vicarious or contributory liability for the acts of the named insured and eliminating the possibility that the endorsement would respond when the additional insured alone was negligent.
The New York Court of Appeals confirmed this reading in its seminal 2017 decision Burlington Insurance Co. v. NYC Transit Authority, 29 N.Y.3d 313 (2017). In Burlington, the court held that the “caused, in whole or in part” language requires proximate causation by the named insured — not mere “but for” causation — and that an additional insured may not obtain coverage where it is the sole proximate cause of the injury and the named insured bears no legal fault. Id. at 318; see also Maroney v. New York Cent. Mut. Fire Ins. Co., 5 N.Y.3d 467, 472 (2005). As the Court explained, “[t]his change was intended to provide coverage for an additional insured’s vicarious or contributory negligence, and to prevent coverage for the additional insured’s sole negligence.” Id. at 326.
In the wake of this change, insurers have frequently asserted that the “caused, in whole or in part, by” language covers only situations in which the additional insured is strictly vicariously liable for the named insured’s conduct. Using this argument, insurers attempt to deny coverage entirely if the additional insured faces any allegations of its own independent negligence. This argument may appear superficially compelling, but as court after court has recognized, it simply does not square with the endorsement’s text.
The Burlington Court itself was careful to distinguish between the additional insured’s sole negligence, which the endorsement does not cover, and the additional insured’s contributory negligence, which it plainly does: “[t]his change was intended to provide coverage for an additional insured’s vicarious or contributory negligence, and to prevent coverage for the additional insured’s sole negligence.” 29 N.Y.3d at 336 (emphasis added). In other words, the endorsement excludes coverage only at the extreme margin, where the named insured bears zero fault. Where the named insured is even partially at fault, the additional insured’s own concurrent negligence does not defeat coverage. Courts applying Burlington have reinforced this reading: so long as the named insured is more than zero percent at fault, the additional insured endorsement is fully triggered, and the insurer may not apportion or cap its indemnity obligation to match the named insured’s share of liability. Starr Indem. & Liab. Co. v. Excelsior Ins. Co., 516 F. Supp. 3d 337, 348–49 (S.D.N.Y. 2021) (holding that additional insured coverage is triggered “where the named insured is more than 0% liable for the underlying plaintiff’s injuries,” and rejecting any attempt to cap the insurer’s obligation at the named insured’s proportionate share of fault).
The insurers’ “vicarious-liability-only” restriction on additional insured coverage has fared poorly outside of New York as well. In Capital City Real Estate, LLC v. Certain Underwriters at Lloyd’s London, 788 F.3d 375, 380 (4th Cir. 2015), the Fourth Circuit held that the endorsement “provides for exactly what it says” and emphasized that “there is no mention of vicarious or derivative liability in the Endorsement.” The Southern District of Texas reached the same result, noting the words “derivative” and “vicarious” are “conspicuously absent” from the form. American Empire Surplus Lines Ins. Co. v. Crum & Forster Specialty Ins. Co., No. Civ. H-06-0004, 2006 WL 1441854, at *7 (S.D. Tex. May 23, 2006). The First Circuit agreed, adding that vicarious liability “cannot be caused ‘in part,’” further undermining the insurer’s position. Scottsdale Ins. Co. v. United Rentals (N. Am.), Inc., 977 F.3d 69, 73 (1st Cir. 2020). Recently, the District of New Jersey undertook a comprehensive survey and identified a “national consensus” that the “in whole or in part” phrase “is consistent with a duty to defend that applies in both direct and vicarious liability contexts.” Navigators Specialty Ins. Co. v. Citizens Ins. Co. of Am., 739 F. Supp. 3d 259, 267–68 (D.N.J. 2024).
Note, however, that not every jurisdiction has embraced this majority position. Florida is the most prominent outlier. In Garcia v. Federal Insurance Co., the Florida Supreme Court held that an additional insured provision covering liability “because of acts or omissions” of the named insured limits coverage to the additional insured’s vicarious liability alone. Garcia v. Federal Ins. Co., 969 So. 2d 288 (Fla. 2007). Federal courts applying Florida law have extended that reasoning to the “caused, in whole or in part, by” language. See, e.g., Cincinnati Specialty Underwriters Ins. Co. v. KNS Group, LLC, 561 F. Supp. 3d 1298, 1314–15 (S.D. Fla. 2021); Utica Mut. Ins. Co. v. Nat’l Fire Ins. Co. of Hartford, 2026 WL 2224899 (N.D.N.Y. Aug. 3, 2026) (applying Florida law). Additional insureds operating in Florida or subject to Florida choice-of-law provisions should be aware of this contrary authority. Nevertheless, the weight of reasoned decisions nationally continues to favor the broader reading that if an insured is more than zero percent at fault, the additional insured endorsement is triggered.
Link to What This Means for Policyholders What This Means for Policyholders
The ‘caused, in whole or in part, by’ language in CG 20 10 means precisely what it says: the endorsement provides coverage when the named insured’s acts or omissions are a proximate cause of the injury, regardless of whether the additional insured also bears fault. Court after court has confirmed this reading.
Policyholders should not accept a denial of additional insured coverage at face value merely because they bear some independent fault. They should read the full policy and endorsement — not just the certificate of insurance — and confirm which edition of CG 20 10 applies. With that said, they should also understand how choice-of-law provisions may affect the analysis, particularly in Florida, where the Garcia decision remains a live obstacle.
[1] See ISO Form CG 20 10 07 04 (emphasis added).
[2] See ISO Form CG 20 10 10 10 01 (emphasis added).