Regulatory peer review can provide a useful check on the methods used to develop science-based regulatory documents. In particular, it is a good way to ensure that erroneous assumptions or faulty data are not relied upon in those documents. However, depending on the complexity of the document and the scope of the charge given to peer reviewers, the peer review process will require great care in the implementation of the peer review process, from the selection of reviewers to the drafting of the final review report. In this talk, I will describe a spectrum of expectations for the peer review process. As potential expectations increase, so do the difficulties and fundamental dilemmas for the peer review process. This talk will describe those dilemmas (e.g. the desire to avoid conflicts of interest vs. the need for a range of expertise, or the needs for balance in peer review panels vs. the desire for consensus in the outcome) as well as why they are unavoidable if one wants a great deal of assurance from regulatory peer review.