Iowa gives a joint legislative committee, called the Administrative Rules Review Committee, significant power over agency rulemaking. The ARRC can delay a rule, either for a 70-day period, or until the end of the next legislative session. It can also object to a rule, which switches the burden of proof to the agency in any future judicial challenge and makes the agency liable for the litigation costs of successful challengers. In this article, the authors study fifteen years of ARRC activity to determine how the committee has used its authority, in order to assess the degree to which this mechanism allows legislative intrusion on executive administration. The data indicate that the ARRC has used its powers selectively, targeting certain agencies for closer scrutiny. Moreover, although the annual number of objections and delays has been relatively small, the overall impact of the review process extends beyond the formal actions taken by the committee. The article then subjects the ARRC procedure to a separation of powers analysis and concludes that the objection and delay authorities exceed the permissible boundaries of legislative power.