The NLRB's 1984 decision in Olin Corporation established new guidelines making it more likely that the Board and its Regional Offices would defer, in unfair labor practice cases, to the prior decisions of arbitrators in those cases. Analyzing case file data in two NLRB Regional Offices for the January 1983-June 1985 period, the author questions the validity of some assumptions underlying the Olin decision and raises concerns about the consequences of the decision. She finds that the two offices frequently deferred to, and infrequently dissected, arbitral opinions even before Olin, and that subsequently the percentage of cases deferred rose even higher. Furthermore, following Olin, the Board's Division of Advice promulgated, and at least one of the two Regional Offices apparently adopted, an inferential form of analysis that may compromise the statutory rights of charging parties—particularly individual charging parties.