49 CFR §601.22

1. (a)Unless the Administrator, for good cause, finds a notice is impractical, unnecessary, or contrary to the public interest, and incorporates such a finding and a brief statement of the reasons for it in the rule, a notice of proposed rulemaking must be issued, and interested persons are invited to participate in the rulemaking proceedings involving rules under an Act.
2. (b)For rules for which the Administrator determines that notice is unnecessary because no adverse public comment is anticipated, the direct final rulemaking procedure described in § 601.36 may be followed.