The FTC recently released its long-awaited Green Guides–or, more formally, Guides for the Use of Environmental Marketing Claims. As their name indicates, the Guides lay out general principles and a few specific examples of how advertisers should make environmental claims in marketing and packaging. Advertisers who fail to follow the FTC’s Green Guides run the risk of being sued by the FTC.

Marketers must always take care not to make “unfair or deceptive” marketing claims. This prohibition includes more than outright lies and deceptions. It extends to all reasonable interpretations and implications of a marketing claim. Everything that is implied, and every reasonable interpretation of a claim, must be supported by data. When it comes to green claims, a marketer should always have support from “competent and reliable scientific evidence.”

Grand assertions are allowed in some settings. But not with green claims. The FTC says that “marketers should not make unqualified general environmental benefit claims.” Don’t say that your product is “green” or “good for the environment.” It’s simply not possible to substantiate every possible interpretation of these claims. On its explanatory conference call, the FTC advised that use of the label “eco friendly,” for example, should be qualified with enough specifics to make the claim accurate. In other words, the FTC wants consumers to know what about the product makes it so “eco friendly”? Is it the packaging? The design? Its rate of decomposition?

Advertisers should also take note that claims are considered deceptive even if they are literally true when the claim creates a false impression based on a natural implication. For example, the FTC says that if you promote a product has having been manufactured in a process that is free of a specific harmful chemical, that claim is deceptive if the chemical was simply replaced by a different harmful chemical.

In general, the FTC isn’t looking for an absurd degree of precision in green claims. If some minor aspect of your product makes your green claims untrue, so long as the claim is substantially true of your product, you’ll be fine. If you say that your packaging is recyclable, but one component isn’t–like an un-recyclable cap on a recyclable bottle–the claim will not be deemed deceptive. The FTC is just looking for honesty, supportable claims, and reasonable disclosure.

And that’s what it comes down to. The FTC’s Green Guides rest, like most other advertising rules, on the concept of disclosure. Always give consumers enough information so that they are not mislead, and you won’t find yourself in trouble with the FTC.