What it means:
Basically, if someone is caught trafficking in a drug that no law exists for, it must be treated as a drug that is chemically similar to the new one, or one that has a similar effect.

Federal Analog Act of 1986

Appendix A

Controlled Substance Analogue Enforcement Act of 1986

P.L. 99-570. Subtitle E, Title I.

SEC. 1202. TREATMENT OF CONTROLLED SUBSTANCE ANALOGUES

Part B of the Controlled Substances Act is amended by adding at the end of the following new section:

"TREATMENT OF CONTROLLED SUBSTANCE ANALOGUES"

"SEC 203. A controlled substance analogue shall, to the extent intended for human consumption, be treated, for the purposes of this title " and title III ("Interdiction") as a controlled substance in schedule I."

SEC 1203. DEFINITION.

Section 102 of the Controlled Substances Act (21 U.S.C. 802) is amended by adding at the end thereof the following: "(32)(A) Except as provided in subparagraph (B), the term `controlled substance analogue' means a substance ---

"(i) the chemical structure of which is substantially similar to the chemical structure of a controlled substance in schedule I or II;
"(ii) which has a stimulant, depressant, or hallucinogenic effect on the central nervous system that is substantially similar to or greater than the stimulent, sic depressant, or hallucinogenic effect on the central nervous system of a controlled substance in schedule I or II;
"(iii) with respect to a particular person, which such person represents or intends to have a stimulant, depressant, or hallucinogenic effect on the central nervous system that is substantially similar to or greater than the stimulant, depressant, or hallucinogenic effect on the central nervous system of a controlled substance in schedule I or II.

"(B) Such term does not include ---

"(i) a controlled substance;
"(ii) any substance for which there is an approved new drug application;
"(iii) with respect to a particular person any substance, if an exemption is in effect for investigational use, for that person, under section 505 of the Federal Food, Drug, and Cosmetic Act (21 U.S.C. 355) to the extent conduct with respect to such substance is pursuant to such exemption; or
"(iv) any substance to the extent not intended for human consumption before such an exemption takes effect with respect to that substance.".

SEC. 1204. CLERICAL AMENDMENT.

The table of contents of the Comprehensive Drug Abuse Prevention and Control Sct of 1970 is amended by inserting after the item relating to section 202 the following new item: "Sec. 203. Treatment of controlled substance analogues.".