Is "Fair Trade" supposed to be capitalized?

No! Do not capitalize fair trade. Only if and when some corporation or government agency or other wicked entity has (ab)used those words to name a specific product or bill (for consumption and confusion of the masses) in which case you’d be referring to that specific abomination.

By itself, it is not a proper noun. Lowercase.

It is capitalized if it refers to specific legislation but not if it does not.

Yes, it should be capitalized if it refers to the Fair Trade certified social movement to benefit developing countries.

@Jeruba I think @YARNLADY makes a strong case for capitalization.

By itself, it is not a proper noun.

Any word or expression used in some special sense could be the proper name of something. Usually there is a context clue of some kind. In that case it would be capitalized. But we don’t go around capitalizing all the words in the language just because they might be the formal name of something somewhere. For starters, just looking at the names of a handful of Fortune 1000 corporations here in Silicon Valley, we’d have to capitalize these words every time we used them:

adobe
apple
intuit
juniper
oracle
sun

But we don’t. We capitalize them only when we are speaking about the entities that have adopted them as their names.

In the absence of other indicators—i.e., by itself—“fair trade” is not a proper noun. Lowercase.

@Jeruba Very good explanation.

@Jeruba After examining how it is used on Wikipedia, I agree that lower case applies.

Wikipedia is not an authoritative source an is rejected by many schools and colleges as an acceptable reference.

Great, thanks all! Now I know, fair trade in capitals refers to the certified movement.

Yes and no.