Employment Division, Department of Human Resources of Oregon v. Smith effectively removed all protections traditionally accorded the free exercise of religion. RFRA was designed to undo the effects of this decision by presumably setting back the clock of jurisprudence to the day before Smith. Even if RFRA is found to be constitutional, it will still, of itself, be ultimately ineffective since it undoes the effects of Smith without addressing the confluence of issues which made a decision like Smith likely. The clock may be set back, but without significant changes it can be expected to run forward again in much the same manner as it did the first time.
The probable worries which necessitated Smith were the combination of a broad definition of religion with a generous policy of religious accommodation. While each factor is easily defensible alone, in our hugely pluralistic society their joint operation could stultify every government action.
One solution would be to systematically limit the reach of the Free Exercise exemptions without compromising either our evolved understanding of "religion" or our traditional interpretation of the constitution. Such an approach encourages the crafting of limiting principles which would restrict the present ubiquity of Free Exercise claims. While these principles would deny Free Exercise protections to some, they would do so in a rational and even-handed way, and only to the extent necessary to trim back the universe of potential claims so that the core intent -- discarded under Smith -- can be preserved.
The five proposed principles to limit Free Exercise protections are: (1) Individuals are better protected than groups; (2) Central beliefs and activities are better protected than peripheral, derivative, or subsidiary beliefs and activities; (3) Beliefs and actions which place demands on the believer him- or herself are better protected than those which place the demands on other persons; (4) Free Exercise accommodations are to be withheld if their grant would raise Establishment concerns; and (5) When religious activities clash with external conditions, the temporally prior state takes precedence.
Donovan, James M., "Restoring Free Exercise Protections by Limiting Them: Preventing a Repeat of Smith" (1996). Law Faculty Scholarly Articles. 454.