A statute passed by Congress is rarely detailed enough to operate on its own. Turning it into enforceable requirements is the work of federal agencies, and the process has defined stages.
Statutes delegate the details
Legislation typically states an objective and authorises an agency to issue regulations achieving it, because the technical content changes faster than statutes can be amended.
The scope of that delegation determines how much discretion the agency has, and disputes about scope are among the most consequential in administrative law.
Agencies must act within the authority granted, and a rule exceeding it can be set aside by a court regardless of its merits.
Proposed rules are published for comment
An agency publishes a proposed rule together with its reasoning and the evidence relied upon, opening a period during which anyone may submit comments.
Comments are not votes. The agency must consider significant objections and respond to them, but it is not bound by the balance of opinion.
The exchange builds a record, and that record is what a reviewing court examines if the final rule is later challenged.
The final rule must answer the record
When issuing a final rule, an agency publishes a preamble addressing substantive comments and explaining any changes from the proposal.
A rule that ignores significant contrary evidence is vulnerable, since courts examine whether the agency considered the relevant factors and explained its conclusion.
This requirement is why preambles are frequently far longer than the regulatory text they accompany.
Review stages sit around the process
Significant rules undergo executive review before publication, including analysis of costs and benefits, which occurs before the public sees the proposal.
Congress retains mechanisms to disapprove rules within defined periods, and appropriations can restrict how a rule is implemented.
Each layer adds time, which is a substantial part of why years can pass between a statute's enactment and its practical effect.
Guidance operates alongside regulation
Agencies also issue guidance explaining how they interpret existing rules, which does not carry the force of law but shapes expectations.
Because guidance can be issued without notice and comment, its use is contested where it functions as a requirement in practice.
Procedures, review requirements and the treatment of guidance change with administrations and with court decisions, so the current position is a matter for specialist advice.