The Sate of California Workers’ Compensation Appeals Board (WCAB) in a February 3, 2009, decision in the consolidated cases of Almaraz vs SCIF et al. and Guzman vs Milpitas Unified School District (Almaraz/Guzman) concluded that the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Fifth Edition, portion of the 2005 Permanent Disability Rating Schedule is rebuttable. The effects of this decision are significant for California and could catalyze challenges regarding use of the AMA Guides in other jurisdictions. Unavoidable consequences of this decision include increased confusion in the assessment of permanent impairment and disability, far more litigation, increased medical and legal costs, and delayed case closure. The consequence of the WCAB's interpretation is significant financial and human costs, including inaccurate expectations by employees regarding the amount of benefits they may reasonably expect, delays in obtaining these benefits, and perceptions of being significantly permanently disabled. Further, the WCAB decision confuses the concepts of “work impairment” and “disability” and presents misleading information about the AMA Guides and its role in assessing impairment. The WCAB decision will be appealed to the Supreme Court, and it likely will be overturned. In the interim, stakeholders must continue to ensure that impairment ratings and resulting disability ratings are accurate. The article reports on and comments in depth regarding the WCAB Decision and highlights errors in the decision.