The regulations in this part implement 42 U.S.C. § 503(l). 42 U.S.C. § 503(l) permits States to enact legislation to provide for State-conducted testing of an unemployment compensation applicant for the unlawful use of controlled substances, as a condition of unemployment compensation eligibility, if the applicant was discharged for unlawful use of controlled substances by his or her most recent employer, or if suitable work (as defined under the State unemployment compensation law) is only available in an occupation for which drug testing is regularly conducted (as determined under this part). 42 U.S.C. § 503(l)(1)(A)(ii) provides that the occupations that regularly conduct drug testing will be determined under regulations issued by the Secretary of Labor.