According to this analysis, many of the sites taken down by onymous were legal:
There are almost 200 sites that have been seized that are not mentioned in any seizure notice or press release. These include the (real) sites for Fish Squad, Exposed, Hack the Planet, Cash Machine, DOXBIN, Pink Meth, OnionSphere, Mr Ouid’s Forum. That list includes personal websites, forums or other sites that had no outward appearance of illegal activity, and they are also not mentioned in any court or press documents. These sites were seized with what appears to be no, or little legal justification.
Is there any indication of the people whose webpages were taken down apparently illegally have sued and/or intend to sue the FBI and/or any other entity over the apparent illegal seizure? Is there any indication of Class action lawsuit being prepared in this matter?