The Digital Millenium Copyright Act has a safe harbor provision for service providers for copyright infringement (see 17 USC 512). These safe harbor exemptions are very important for companies which archive information (e.g., Google) and utilize user-generated content (e.g., YouTube and Yelp). The service provider is not directly liable if they meet *all* of the conditions for exemption. If a service provider fails to meet any of the conditions, then the safe harbor exemption does not apply, end of story.
Many people seem to know the general conditions for exemption outlined in Section 512(c). A service provider shall not be liable ... if the service provider:
(A)
(i) does not have actual knowledge that the material or an activity using the material on the system or network is infringing;
(ii) in the absence of such actual knowledge, is not aware of facts or circumstances from which infringing activity is apparent; or
(iii) upon obtaining such knowledge or awareness, acts expeditiously to remove, or disable access to, the material;
(B) does not receive a financial benefit directly attributable to the infringing activity, in a case in which the service provider has the right and ability to control such activity; and
(C) upon notification of claimed infringement as described in paragraph (3), responds expeditiously to remove, or disable access to, the material that is claimed to be infringing or to be the subject of infringing activity.
However, a lesser known one seems to be the requirement to file an Interim Designation of Agent to Receive Notification of Claimed Infringement with the Register of Copyrights.
Section 512(c)(2) is very clear on this:
(2) Designated agent.— The limitations on liability established in this subsection apply to a service provider only if the service provider has designated an agent to receive notifications of claimed infringement described in paragraph (3), by making available through its service, including on its website in a location accessible to the public, and by providing to the Copyright Office, substantially the following information:
(A) the name, address, phone number, and electronic mail address of the agent.
(B) other contact information which the Register of Copyrights may deem appropriate.
Side note: There is some debate if service providers are exempt from any liability (direct, contributory, or vicarious liability) for copyright infringement, or if they are only exempt from direct liability.
Hat tip to Eric Goldman