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When Congress enacted the Hatch-Waxman amendments to the Federal Food, Drug, and Cosmetic Act (FDCA) in 1984, creating a statutory pathway for abbreviated new drug applications (ANDAs), it included an incentive for generic applicants to challenge as invalid, or alternatively design around, patents claiming the innovative drugs on which they based their abbreviated applications.' In brief, the first generic applicant to file an ANDA asserting that such a patent was invalid or not infringed would be awarded 180 days of generic market exclusivity. During this exclusivity period, the Food and Drug Administration (FDA) could not approve a subsequent ANDA that challenged a patent claiming the same drug. This is the fourth in a series of articles explaining the law of 180-day exclusivity. Like the others, it takes a descriptive and doctrinal approach to the law that has emerged from the statute, the agency's implementing materials (which range from regulations to citizen petition responses and decisions to award or deny exclusivity), and court decisions. Its scope is, however, slightly different.

Section I of this article provides the necessary background regarding the statutory language as well as a high-level description of the steps FDA has taken to implement the scheme. It defers discussion of the details of FDA's implementing regulations to section II. Section II discusses the discrete interpretive issues, arranged in five categories: which rules apply, earning exclusivity, forfeiture of exclusivity, commencing the exclusivity term, and enjoyment (use) of the exclusivity term. This section presents each issue as a question and then offers a short answer and a more full discussion. In some cases, the issue is sufficiently discrete and the discussion sufficiently brief that the article dispenses with a "short answer" altogether. Because FDA has announced that it will release guidance on 180-day exclusivity sometime in 2016, section II flags open issues as well as apparent agency policies that could be confirmed in guidance. We conclude in section III with a brief discussion of lingering and renewed criticisms of the scheme, in the courts, academic literature, and Congress. We note a variety of proposals, both in Congress and in the secondary literature, to change the scheme yet again.



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