kaled - 9:47 am on Oct 12, 2010 (gmt 0)
the POST data does not exist on the page created by the post
This is getting silly - try hitting the refresh button whilst viewing a page resulting from POST. Depending what browser you are using you will probably be asked whether you wish to resend that data. In other words, browsers typically remember the POST data that was used to create the current page, therefore it is a trivial matter to save that data as part of a bookmark.
However, even if current browsers did not cache the POST data for the purpose page refreshes, it would be trivial to do so and thereby enable bookmarking.
A piece of advice - when someone tells you that solving a problem is trivial, instead of assuming they are stupid or ignorant, try to figure out how you would solve that problem - you might discover that it really is trivial after all.
Taking your example, it is entirely possible that a user could arrive at your page after searching for a small subset of the keywords stuffed into the URL, for example, Personal Family Relationships. Also, there could be several other keywords in the original search that only appear in the text not the url. Therefore, it does not follow that the breach of privacy (if there is such a breach) is as great as that of a search engine which supplies the absolute, precise list of keywords used with none missing and no extras.
You're over-reaching with your argument here!
There is actually a serious problem here with respect to UK law. Given that the IP address is also available and this can be used to identify the user (absolute certainty is not required under UK law) then under certain cirmstances, the search information could be considered private which then takes us into the realms of the Data Protection Act. For instance, it is easy to imagine that someone with cancer might search for certain specific keywords and some of those might be pretty obscure, the sort only used by a doctor to a patient (i.e. there would be a high probability that the user actually had cancer).
Now, since there is no obvious way to contact someone using only their IP address, such information might be of low value, but we do know that advertisers are always looking for new ways to promote goods and it is entirely possible that a list of IP addresses of people researching cancer would have some value even if the list had a short life because IP addresses change.
So, following this argument, it is possible that an agency other than Google could stuff subtle adverts onto pages promoting dubious drugs to vulnerable people. We all know that what I have described is technically possible even if it hasn't actually happened yet.