Comment by mtlynch

That's useful context, thanks!

Though I think the sentence immediately after the one you quoted is also relevant:

> However, practices inconsistent with the Guides may result in law enforcement actions alleging Section 5 violations.

My understanding is that there's no law that says, "You have to disclose if you're an affiliate earning commissions on a recommendation," but the FTC is saying that they interpret Section 5 of the FTC act to imply that, and they may prosecute people under that interpretation, which they have done.[0, 1]

[0] https://www.ftc.gov/system/files/documents/cases/160523lordt...

[1] https://www.ftc.gov/legal-library/browse/cases-proceedings/1...