Final answer:
Article 112a of the UCMJ addresses the possession and use of illegal substances, including those controlled under the CSA, and prescribes severe punishments for violations.
Step-by-step explanation:
Under the Uniform Code of Military Justice (UCMJ), the possession of or use of illegal substances is typically addressed under Article 112a. This article explicitly deals with the wrongful use, possession, distribution, manufacture, and importation of controlled substances, including any substances listed on the Controlled Substances Act (CSA). The consequences of violating this article can be severe and may include court-martial, imprisonment, and dishonorable discharge from the military service.
Additionally, it's noteworthy to mention that marijuana remains a controlled substance under federal law, despite some states legalizing it for medical or recreational use. The federal law, as dictated by the CSA, takes precedence over state laws when it comes to military justice and federal prosecution. This can lead to a clash of state and federal laws, especially considering that the armed forces follow the federal law as stated in the UCMJ.