GAO issued a decision on 31 Jan 06 in DOR Biodefense Inc. and Emergent BioSolutions, B-296358.3 and B-296358.4 regarding whether a modification is within the scope of the original competition under the Competition In Contracting Act (CICA). Modifications outside the scope of the original competition must be competed or justified as sole source actions. Scope analysis is not mechanical, but requires an integrated assessment of multiple factors, including contract type, specification or statement of work, cost and performance period. Whether the modification requires competition also depends upon whether the original solicitation adequately advised offerors of the potential for that type of change, and thus whether the modification would have changed the field of competition. In Biodefense, the Army issued a single award ten year indefinite quantity contract for development and certification of vaccines for biological defense. The challenged modification was exercise of an optional CLIN for development of a type of vaccine not expressly listed in the solicitation's option that extended the performance period for the option by 8 years at a significant increase in cost. The GAO determined that this modification was, nevertheless, within the overall scope of the original competition based on the broad developmental purpose of the contract and the solicitation's express notice to offerors that additional vaccine types could be added after award and that changes in regulation may affect performance period and costs. The discussion of actions taken by the Army in the original solicitation to put competitors on notice of the potential for post-award modifications provides good practice insight.