It has been 10 years since the Insurance Services Offices, Inc. (“ISO”) issued the fault-based version of its CG 20 10 additional insured endorsement. The 2004 endorsement, Form CG 20 10 07 04, replaced the widely litigated phrase “arising out of” with a more restrictive requirement that the additional insured’s liability be “caused, in whole or in part, by” the “acts or omissions” of the named insured. ISO touted the 2004 revisions as the industry’s solution to the overly broad judicial interpretations of “arising out of” that have afforded coverage for the additional insured’s sole negligence and other unintended transfers of risk. Nevertheless, ISO’s effort to achieve a narrower interpretation has been met with inconsistent and sometimes perplexing results. Some courts have interpreted the endorsement as requiring negligence while others have limited the coverage grant more strictly to vicarious liability.