There are many statutes that involve criminal activity relating to controlled substances. Generally, it is a crime to:

• Possess illegal drugs
  
• Possess illegal drugs for sale
  
• Transport illegal drugs
  
• Be under the influence of certain drugs
  
• Sell something that you say is an illegal drug
  
• Manufacture illegal drugs

The impetus of most drug laws focuses on curtailing the use of drugs, but there are a few laws that focus on observing drug use and transporting drug paraphernalia.

The Prosecutor's Duty
Generally with most drug crimes, the prosecution must prove that the defendant knew it was a controlled substance and that the drug was present.

This is usually the easiest element to meet because the prosecution can show that the drug was found on the defendant or among the defendant’s things.

Sometimes a prosecutor may show that the defendant was involved with controlled substances in the past, though this could create a circumstantial character evidence problem.

Knowledge & Presence
This element of the crime is usually not too difficult to meet if it can be shown that the drug was found in the defendant’s personal belongings, or in a place only the defendant had access.

But if the person was merely around the controlled substance and had no idea that it was there, he/she will probably not have knowledge of the drug’s presence.

Need for Useable Quantity
Another required element is that the drug needs to be a useable quantity. Residue that is worthless for sale or use will not sustain a controlled substance charge.

However, drugs cut with a large amount of another legal substance will not provide a defense to a drug charge, because passing something off as a controlled substance is still a crime.