The primary focus for research regarding the federal drugs should begin with Title 21 of the United States Code, Section 841. In Section 841(a) of that title, the statute lists all of the prohibited acts relating to the federal drug laws. In Section 841(b) of that title, the statute sets out all of the various penalties associated with different types of illegal drugs.
Federally, drug crimes are punished based upon the amount and type of drug involved in the particular offense. You have expressed an interest in researching cocaine, crack cocaine (referred to as cocaine base in the statute) and heroin. All of those drugs are individually listed in Section 841(b).
For example, a first offender with 50 grams of crack cocaine would be facing a statutory sentence of a mandatory minimum of 10 years to a maximum of life incarceration, a $4,000,000 fine and 5 years of supervised release (which is like a period of probation after a defendant is released from jail).
For federal crimes involving simple possession of controlled substances, you should look at Title 21 of the United States Code, Section 844. That particular statute also lists the penalties for simple possession. The federal drug statutes are fairly straight forward and easy to understand.
However, the actual sentences for federal drug cases is further complicated by the advisory Federal Sentencing Guidelines that judges use to sentence drug offenders. Entire courses are aimed at teaching federal prosecutors about the various Guidelines associated with sentencing drug offenders. Even under the Federal Sentencing Guidelines, punishment for drug offenses is largely driven by the amount and type of drug at issue.
Unlike the mandatory punishments found in the statute (Title 21 mentioned above), judges have much more discretion under Guideline sentencing. If you are brave enough to want to explore the Federal Sentencing Guidelines, a good starting point would be the United States Sentencing Guidelines, Section 2D1.1. All of Part D of the Guidelines deals with drug offenses.
Information provided by US Attorney's Office, early in 2007