Whether you live in a state where marijuana is legal or not, seeing those flashing red and blue lights in your rearview mirror when you're driving in possession of cannabis can be scary.

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The laws around driving with cannabis vary dramatically from state to state — and in several states where the plant has been legalized for medical or recreational use, there are ways to do it legally. But that doesn't change the fact that getting pulled over with pot can induce some serious anxiety. Here are some dos and don'ts for driving with weed.

DO

1. Put your pot in the trunk or a glove box.

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When you're on the road in one of the 25 states where marijuana is legal for medical or recreational purposes, treat cannabis as you would alcohol. There are open container laws that prohibit drivers from keeping an open bottle or can in the car, but you're allowed to transport alcohol if it's sealed up properly. The same rules apply to marijuana in legal states, so when transporting cannabis, the best practice is to keep the substance — unopened and unused — in the trunk or in a glove box, Vice reported.

2. Keep it under an ounce of cannabis (or four grams of concentrate).

If you're a legal medical marijuana user, or an adult 21 or older in a recreational state, you can legally possess up to one ounce of marijuana (or four grams of concentrate) in your vehicle. Though there are penalties for possessing more than an ounce in a legal state, they tend to be minor (the charge is an infraction in California, for example). But if you're transporting marijuana illegally, any amount over an ounce carries more severe penalties; it's a misdemeanor charge punishable by a maximum of six months in jail and/or a $500 fine in California, according to NORML.

DON'T

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1. Eat your weed.

Do not — under any circumstances — attempt to eat or discard your marijuana if you're pulled over by a police officer. Getting caught attempting to discard your weed can bump your misdemeanor possession charge up to a third-degree felony charge for "tampering with evidence." There's a simple song, called "Don't Eat Your Weed," which was created by two Texas criminal defense attorneys last year that should help you remember this rule:

2. Travel across state lines.

You might assume that driving from California to Oregon with weed would be fine; after all, both states have legal marijuana systems. But transporting marijuana across state lines — regardless of the states' marijuana laws — is a serious federal crime, reaffirmed in a 2013 memo from the U.S. Department of Justice.

"Even if you're bringing marijuana from Washington to Oregon — where it's legal in both states — you're still entering the Cole memo's enforcement priorities by moving it across state lines, and there are federal implications to that," Daniel Shortt, an attorney who specializes in cannabis law at Harris Bricken, told ATTN:. "It's important to realize that driving is still a sensitive area with regard to cannabis and to be informed about possession laws and driving laws, and to watch out for state lines."

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3. Consume cannabis while driving.

This should probably go without saying, but driving under the influence of marijuana remains strictly prohibited — in both legal and illegal states. Do not smoke or consume edibles before driving if you want to avoid legal trouble. Though there are efforts underway to develop a marijuana breathalyzer and set standards for impairment similar to that of alcohol, the science hasn't caught up yet. And law enforcement has broad discretion when it comes to determining impairment from marijuana use and appropriate punishment, which could involve anything from a fine to jail time to a license suspension, according to NOLO.

While these are just meant to be helpful guidelines, the most important thing to keep in mind is that laws vary from state to state. So any time you're thinking about driving with cannabis in a legal state, consult your state and local laws. If you live in a state where marijuana is illegal, at least be sure not to consume before driving — and definitely don't try to eat your weed if you get pulled over.