Driving with your stash in tow is not as simple as you might think.Cannabis may be fully legal in 21 states, but the rules regarding the use of weed vary widely across the country, with different states having entirely different laws. Whether in-state or across state lines, the rules around driving with marijuana can get a little, well, hazy.

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To help you avoid breaking the law, we’ve put together this easy guide with everything you need to know about driving legally with weed.

Can you drive across state lines with weed in your car?

When traveling with cannabis, there’s one country-wide rule you need to remember: you can’t drive across state lines with weed. This applies everywhere in the US, regardless of whether the cannabis has been purchased legally. Even if you’re traveling between two states where cannabis is fully legal, it’s still considered a federal crime to take weed across a state border, since cannabis is illegal at a national level.

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The DEA states that a first offense of carrying less than 50kg of marijuana across state lines can result in a 5-year prison sentence and a $250,000 fine.

This is true for medical marijuana too. Because medical marijuana is still illegal under federal law (it’s the only state law that has made it legal in some areas), crossing borders with it in your car or on your person is a federal crime. If you rely on medical marijuana, your best bet is to travel to a state where it’s legal and pick up a new prescription while you’re there.

Do open-container laws apply to cannabis?

Open-container laws refer to traveling with an open supply of a substance, usually alcohol. In some states, you can’t drive with an open bottle of alcohol in certain areas of the car, as it’s a sign you may have been drinking it. But is this the same with weed?

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Essentially, yes. While details on the laws do vary from state to state, one law that exists virtually across the board is that weed must be kept in a sealed, unopened container at all times while traveling in a car. If it’s found with a broken seal, you could face charges of both fines and prison time.

To be clear, this law applies in states where cannabis is fully illegal. Having cannabis in your car in a state where cannabis is not legal will, naturally, result in a much more serious penalty.

Many states also require you to keep your sealed container of cannabis in the trunk of your car, or at least away from the driving area (such as in the back seat) if you don’t have a trunk. The best idea is to play it safe and put your stash in the trunk wherever you are.

An exception to this is Oregon. Oregon law states that any person over 21 can transport an ounce of cannabis around the state, but the law does not specify any rules regarding how weed should be transported. Our advice? Think “how would this look to a judge?” and keep it sealed and away from the driver’s seat.

Can you get a DUI for driving while high?

If you get nothing else out of this article, remember to never drive high—end of story.

When it comes to cannabis laws, this is an important one. It’s illegal in every state, regardless of the legality of marijuana, to drive while high. The offense is similar to a DUI, and you can be penalized in the same ways.

This is true even for medical marijuana. You shouldn’t even consume it in your car, even if you’re not planning on driving, just to be certain you won’t get into trouble. If you’ve used pot outdoors and feel like you might not be feeling the effects anymore, it’s best to wait until it’s completely out of your system before getting behind the wheel.

What are the rules for transporting medical marijuana?

If you’re traveling with cannabis in a state where medical marijuana is legal, the rules for storage are the same. You need to keep it in a sealed container and, usually, away from any passengers. Keep it in your trunk, and you should be fine.

You should also leave the marijuana in its original packaging with all original labels attached. If you have a medical marijuana card, make sure it’s on you and ready to show if you’re questioned. If you’re a business moving medical marijuana, you may need to acquire a cannabis transporter license before doing so.

How similar are cannabis transport laws to alcohol laws?

When it comes to how to travel with weed, you’ll notice that the laws are very similar to driving with alcohol. This is especially true in states where both medical and recreational use of cannabis is legal, allowing anyone over 21 to travel with weed within that state.

You can’t drive under the influence of either substance, and both must be contained and kept away from the driver’s area of the vehicle.

But one situation where the rules really differ is when it comes to crossing state lines. Under US law, you can’t take any marijuana across states, but you can take alcohol as long as it’s only for personal use. (There are a few exceptions to this, though, so be careful to check before you travel with alcohol across borders.)

Stay informed

The law around traveling with weed is something every cannabis user should know, but few fully understand. Even if you’re in a state where weed is legal for adult-use, there will still be some settings where the laws get sticky, and driving with cannabis is one of them.

The best thing you can do to ensure you are transporting cannabis responsibly is to look up the laws on driving with weed in your state. Every state has different laws around driving with cannabis in the car, and they are sometimes very specific. And remember: if you’re driving from one state to another, never cross state lines with cannabis in your vehicle.

If your state’s laws aren’t clear but you live in a state where cannabis is legal, keep your cannabis in a sealed container in the trunk of your car while driving within the state and you should be in compliance with the law.