Twitter is a publication. No matter how casual or hyperbolic the medium, and no matter whether anyone really takes it seriously (as Courtney Love argued in one of her infamous Twibel lawsuits), your statements have consequences. Before you click that blue icon that says “Tweet,” you should mentally clear this checklist.

Are you tweeting a derogatory statement?

You can be sued for defamation if you tweet a derogatory statement of verifiable fact injurious to someone else. Just because you say it’s your opinion doesn’t end the inquiry. Courts look to whether a reasonable reader would understand the statement as asserting a statement of verifiable fact, i.e. a statement that is capable of being proven true or false. Very generally, publication + derogatory false fact about the plaintiff + harm (actual or per se) = defamation. Avoid derogatory comments. Period. Even as a joke. And don’t retweet someone else’s, either.

Are you promoting a contest or sweepstakes?

If you haven’t vetted the contest with your legal team, don’t tweet it. In addition to federal rules, most states restrict lotteries, and some require state registration of the promotion.

A hashtag promotion may be illegal. The FTC requires disclosure of any “material connection” offered in exchange for an online endorsement. This year, the FTC investigated Cole Haan’s “Wandering Shoe” hashtag promotion in which the company solicited contestants to create Pinterest boards of Cole Haan shoes tagged with “#wanderingsole” to win a shopping spree. The FTC did not recommend enforcement action, only because the it “had not previously publically addressed whether entry into the contest is a form of material connection…[and] whether a pin on Pinterest may constitute an endorsement.” But now it has.

Are you falsely advertising or misleading the public?

The FTC Act and state “mini-FTC Acts” prohibit false or misleading advertising, which includes misleading price comparisons, rebates, and sweepstakes promotions. The Securities and Exchange Commission (SEC), too, will police Twitter for statements that violate the Securities Act. This year, the SEC charged Mark Grimaldi, president of Navigator Money Management, Inc., in part, for tweeting that his “cap app model has DOUBLED the S&P 500 the last 10 years.” The SEC charged that he overstated his involvement in the performance of the capital appreciation model for the relevant time period.

Are you promoting a treatment not recognized by the FDA?

The FDA also takes social media seriously. It issued two draft guidances on how the pharmaceutical and medical device industry should use social media. For more information, visit Michael Walsh’s blog “FDA, Social Media & Promotional Labeling” here.

Is your retweet an improper endorsement?

If your company is prohibited by contract or law from endorsing or promoting its products (or those of another) in a certain manner, you may violate those prohibitions by retweeting, favoriting, or liking someone else’sstatement. On June 27, 2014, the FDA issued Zarbee’s, Inc. a warning letter for, among other things, liking, retweeting, and commenting favorably on endorsements by other social media users. The FDA interpreted such action as Zarbee’s adopting the comments of the other users as its own.

Are you tweeting someone else’s intellectual property without permission?

Don’t tweet content created by someone else (e.g. artwork, photos, or videos) without written permission to use it the way that you are using it. Do not assume “stock photos” are safe. They are usually copyrighted, and library owners actively police their copyrights.

Don’t use photos (even your own) of another person without that person’s written permission. On April 9, 2014, Katherine Heigl sued Duane Reade for tweeting an unauthorized paparazzi photo of her leaving a Duane Reade pharmacy with the caption “Love a quick #DuaneReade run? Even @KatieHeigl can’t resist shopping #NYC’s favorite drugstore.”

Are you breaching confidentiality?

Don’t post information about your clients unless you have their express written permission. This is especially true for medical companies, hospitals, law firms, and other professions whose obligations require protecting their clients’ identities and confidential information. Just because you don’t mention the client by name doesn’t mean you’ve avoided a breach. Nor do you want to advertise that you don’t take your clients’ privacy seriously.

If you can’t pass every item in this checklist (which is only a partial one), keep the little blue bird in its cage.