In theory it is possible that requests can be made via sites such as Facebook and Twitter, but to be valid they still have to comply with s8 of FOISA, which requires that requests state the name and address of the applicant and an address for correspondence as well, of course, as describing the information requested.
Requests which are anonymous or which use pseudonyms will not be valid. This is less likely to be an issue with Facebook (Facebook asks users to provide their real name), but may cause problems with Twitter. Although it may be possible to find out the real name of the applicant through a Twitter user's linked profile, the Commissioner takes the view that, for the request to be valid, the name of the requester must be evident from the tweet itself.
As mentioned above, requests must also include an address for correspondence. Given the restrictions on responding (see below), it is preferable if the request contains an email or postal address where a response may be sent.
Where requests do not specify the name of the applicant or an address for correspondence, you should, in line with your duty to provide advice and assistance under s15 of FOISA, tell the applicant what they have to do to make the request valid and how best to use their information rights. Often, the easiest option will be to ask the applicant to make a new request via email or suggest they use www.whatdotheyknow.com. However, if the information can easily be provided, you may instead choose just to disclose the information, while making the applicant aware that the request is in fact invalid.
Public authorities are likely to face difficulties replying to requests made via Facebook or Twitter, particularly if they are refusing to disclose information (given the need to issue a notice complying with s16 of FOISA) or are disclosing large amount of information. (Twitter contains a limit on the number of characters that can be used.) In order to comply with FOISA, public authorities must "give" applicants information (see s1(1)) or "give" a notice (see e.g. s16(1)) explaining why the information is not being provided. It is not yet clear whether providing an applicant with a link where they can access the information or read the notice is sufficient to comply with this duty, although applicants are perhaps unlikely to complain if information is provided, or a notice is given, in this way. Again, the best solution may be to ask the applicant to provide an email or postal address to allow the authority to "give" a response or suggest they use www.whatdotheyknow.com.
The Commissioner has not yet received any applications for a decision following on from a request made via Facebook or Twitter and this is new and untested area. Decisions as to whether requests (and subsequent applications) are valid will be made on a case by case basis and this guidance will be updated to reflect any decisions made.
You should also be aware that requests for environmental information made under the Environmental Information (Scotland) Regulations 2004 may, given that there is no express requirement to provide an address for correspondence, be more likely to be valid if made via Facebook or Twitter than requests under FOISA.
Finally, you need to remember that you are under a duty to provide advice and assistance to requesters. So, if someone seems to be trying to make a request through Facebook or Twitter, the authority should respond.