Dates in the JSON response object are encoded as character strings using the
extended format defined by ISO standard 8601:2004. They are always in UTC.
You can find the ISO standard 8601:2004 at http://www.iso.org/iso/catalogue_detail?csnumber=40874. This is an example of what to expect in a date/time string in a JSON response:
"createdAt" : "2012-07-20T21:46:09.659+0000"