We touch on support for claims in this blog with some regularity—it’s a key factor in communications credibility (and thus the Thinkshift Credibility Quotient™). But with BP’s epic greenwashing staring us in the face every day (remember the green oil company? beyond petroleum?), the credibility of green claims generally may be more suspect than ever. Now feels like the ideal time to unpack what it means to support claims.

Here are three major elements we look for:

Data or testimony from credible third parties. Support from any believable source (fully attributed customer testimonials, for example) can enhance credibility, but verification by a trusted third party is the gold standard. Eco-seals can be a good shorthand way to support claims, but be careful: They have to be well-recognized—if people don’t know what a symbol means, they’re not going to put a lot of trust in it—and they have to have real standards behind them.

Details. The support should be specific and detailed enough to be understandable—and verifiable.

Relevance. To be credible, support has to be relevant to the claim at hand. A great company recycling program isn’t support for a claim that a household cleaning product is green. Nor is a statement that the product is free of some chemical that no product of its type contains. (This is a reverse use of the old advertising ploy of highlighting some common product characteristic so that it appears to be a special feature of your product—Mad Men fans will immediately flash on “Lucky Strike—It’s Toasted.”)

Any time you can’t muster this kind of support is a good time to think about whether you should be making that claim.