With the holiday season approaching, travelers likely have lots of questions about the rules set out by the TSA. Is mascara a liquid? Does a cane count as a personal item? Are ice skates allowed on a plane? And most importantly: Can I fly with my legally obtained marijuana? By Caroline Siede .

It's relatively easy to find out that mascara does indeed count as a liquid, a cane is exempt from the personal item limit, and ice skates are allowed on carry-ons, but it can be much harder to find a straight answer about flying with marijuana.

Earlier this month citizens in Oregon and Alaska voted to join Colorado and Washington as the four states where retail marijuana is legal for adults over the age of 21. Washington, D.C. residents, meanwhile, voted for a "soft legalization" measure. (Vox has a great breakdown of the current state of marijuana legalization.) Medical marijuana is currently legal in 23 states as well as the District of Columbia. It's used to treat conditions ranging from pain and nausea to Parkinson's disease, PTSD, multiple sclerosis, and a host of other conditions. Patients who successfully apply for a medical marijuana card are allowed to possess a limited amount of the substance, which varies by state.

So how does that affect air travel?

THE BAD NEWS



Under federal law marijuana is an illegal Schedule 1 narcotic deemed to have a "high potential for abuse and no medical value." Federal law does not distinguish between medical and recreational marijuana—any form of the substance is illegal. Since airports, airspace, and airplanes all fall under federal jurisdiction, anyone found flying with medical marijuana is at risk of being detained, arrested, and prosecuted under federal law.

THE GOOD NEWS



Across the country once-strict policies are loosening and it seems the TSA is not immune to these changing attitudes. The official TSA policy states:

TSA security officers do not search for marijuana or other drugs. In the event a substance that appears to be marijuana is observed during security screening, TSA will refer the matter to a law enforcement officer. Whether or not marijuana is considered legal under local law is not relevant to TSA screening because TSA is governed by federal law. Federal law provides no basis to treat medical marijuana any differently than non-medical marijuana. Even if an item is generally permitted, it may be subject to additional screening or not allowed through the checkpoint if it triggers an alarm during the screening process, appears to have been tampered with, or poses other security concerns. The final decision rests with TSA on whether to allow any items on the plane.

In other words, TSA is mostly interested in protecting its passengers' safety and less interested in busting those traveling with a small amount of pot. TSA agents are not specifically looking for marijuana and if they do happen to find it in a routine search, it's largely up to the individual TSA agent to decide how to respond. Policy is to report the substance to local law enforcement. In states where medical marijuana is legal, anecdotal evidence suggests local police will often verify a passenger's documents and allow them to fly with medicinal cannabis if everything is in order. However, according to USA Today, the legalization of recreational marijuana in Colorado has resulted in stricter policies that ban pot in the airport but don't penalize passengers for possession (they just need to return it to their cars or throw it away before they go through security).

Still, there seems to be a lot of leeway in these policies. In 2011, TSA agents at Denver International Airport found a small bag of marijuana in the checked bag of rapper Freddie Gibbs. They left the weed along with a note saying "C'mon son." However, that casualness definitely does not extend to larger drug trafficking. When Los Angeles TSA found 100 pounds of marijuana wrapped up as a birthday gift during a bag screening they promptly turned it over to DEA and LAPD.

THE RESOURCES



Many who rely on medical marijuana as part of a treatment plan are understandably confused about where this leaves them when it comes to traveling. Websites liked United Patients Group and Medical Jane attempt to clarify this confusing situation and keep users up-to-date on policy changes.

For those living in states where medical marijuana is legal, the best advice is to call ahead and ask the airport directly. Anecdotal reports suggest that the TSA is particularly accommodating to those with legal medical marijuana cards who are traveling to states where medical marijuana is also legal (or simply traveling within the same state). According to United Patients, both California's Oakland and San Francisco airports are medical marijuana friendly.

In 2013 David Knowles explored the TSA's policies for NY Daily News and suggested that the TSA is at a bit of a crossroads. While the agency remains bound to enforce federal law, in practice it has little interest in actively seeking out drugs. It often falls on individual TSA agents and law enforcement officers to tackle incidents involving marijuana on a case-by-case basis. That makes it hard to give generalized advice to those hoping to travel with marijuana.

THE FACTS

Here are some important points to keep in mind when it comes to traveling with marijuana:

Medical marijuana is currently legal in California, Alaska, Arizona, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, Washington, and the District of Columbia.

Retail marijuana is currently legal for those over 21 in Colorado and Washington. It will become legal in Oregon, Alaska, and the District of Columbia once those states finalize some procedural hurdles.

In every other state but the ones listed above, marijuana possession can result in arrest even if the patient is registered for medical marijuana in his or her home state or if the marijuana was legally purchased in another state.

It is illegal to bring marijuana across state lines (even driving pot from Washington and Oregon will technically be illegal). Medical marijuana users traveling to one of the six states with reciprocity towards medical marijuana cards from other states (Arizona, Maine, Michigan, Nevada, New Hampshire, and Rhode Island) should purchase medical marijuana at their destination rather than travel with it.

The United States is basically a patchwork quilt of policies towards medical marijuana. Each state has separate rules about possession and registration. ProCon has a helpful list of each state's policies, but it's best to research the specific policies of the state to which you are traveling.

On domestic flights, passengers only pass through security at their departure point. That means once a passenger is onboard a plane, it's highly unlikely he or she will be screened again. (This does not apply to international travel.) According to United Patients, TSA does not alert authorities at the destination airport if they allow a passenger to fly with medical marijuana.

According to United Patients: "Several patients have noted the importance of carrying only what is needed for your personal consumption, to be inconspicuous in the manner in which you transport your medicine, and never putting marijuana, edibles, or other related items in checked luggage but always taking it as carry-on. Many patients have shared that when following these guidelines, even without alerting authorities prior to arrival, they have passed through security without a problem, but always carry their documents just in case."

For those who use marijuana legally, the alternatives for traveling are unhappy ones: Either leave the marijuana at home or take the (relatively low) risk of bringing it through security. That situation is unlikely to change until there is a shift in federal policy.

Photo collage created from these CC-licensed images: Cannabis sativa leaf Dorsal aspect: Jon Richfield | Jet: Yuichi Kosio