Legal Question in Entertainment Law in California

"if a member of the band leaves and then trade marks the name." -

-Well if he left and filed a trademark application eventually after the processing is done there is a publication of the mark in the Trademark Official Gazette (TMOG). Within 30 days (notwithstanding timely requests for extensions within those 30 days) of that publication in the TMOG you can file an Opposition with the Patent and Trademark Office. Thus find the publication date. If its timely get the trademark number and file an Opposition. One should get an attorney as its a hearing in the federal system and you could serious prejudice your case without one.

"does he own the name outright even thou there is more than 15 years of recorded history along with poorboy copy written material?"

Technically it is prima facie evidence of ownership in any infringement lawsuit. Another person sued for infringing may rebut that presumption with evidence of the own prior use of the trademark in commerce. After 5 years of using the mark without being contested it becomes for practical purposes invincible (i.e. "incontestable").

"also since on all recorded material were clearly marked on cd/tape/ect. that "all songs written and preformed by(band) do we still have the right to preform sed music?"

The performance of the music by itself, not talking about using the trademark anywhere, is not affected by the trademark as it is a copyright issue to play the music you guys wrote and produced.

Note if you're a serious musician you would be wise to register your original songs with the US Copyright Office.