Using marijuana for medical purposes is now legal in more than half of the United States. Residents in states that still criminalize marijuana commonly ask, "Can I travel across state lines and buy medical marijuana in neighboring states, and bring it back home?"
The short answer is no. If your state doesn't allow medical marijuana, it is illegal to use it in your state, no matter for what purpose, and no matter where you bought it. Even if you have a medical marijuana card from another state, you can be arrested and charged for possession in states where medical marijuana is not legal.
Under federal law, all marijuana, including marijuana used for medical reasons, is illegal. In theory, federal agents can arrest people who are not traveling but who are using marijuana according to state medical marijuana law, but they rarely do. However, transporting a substance that the feds have classed as illegal is another matter. When you cross state lines to transport an illegal substance, you're committing another federal crime called drug trafficking. The penalties for trafficking marijuana include prison and fines of $250,000 or more, depending on the quantity of marijuana.
Flying with marijuana is equally risky. Passengers in airports are subject to the Transportation Security Administration (TSA), a federal agency governed by federal law. All marijuana remains illegal under federal law. TSA's response to the discovery of marijuana during a security screening is the same in every state and at every airport regardless of state law. TSA officers are required to report any suspected violations of law to local, state or federal authorities.
You might be able to travel to one of the states that allows medical marijuana and use medical marijuana while in that state. First, you'll need proof that your medical condition warrants marijuana treatment. The procedure for getting a medical marijuana recommendation from a doctor varies from state to state. Some states require proof of residency and others do not. Typically, it is expensive to get a recommendation and it requires a lot of paperwork.
Rather than trying to obtain a recommendation from a doctor in another state and remaining in that state to use the drug, some people will travel to another state to obtain the substance as a recreational user. Recreational marijuana (use of small amounts only) is legal in eleven states and the District of Columbia. In these states, people 21 and older can purchase and consume marijuana without a doctor's recommendation. "Marijuana tourism" is on the rise, but it's important to know the laws of the state you are visiting. Rules about how, when, and where to consume legal marijuana vary from state to state and even from county to county.
State marijuana laws are a confusing patchwork of regulations that vary from state to state and contradict with federal law. This area of the law is changing rapidly. If you have questions about the limits of legal marijuana, you should contact a lawyer.