Judge Richard A. Schell ruled Sunday that Charles "Tex" Watson waived his right to attorney-client privilege when he allowed the lawyer to sell the tapes to an author.
A bankruptcy court ruled last year that the LAPD should get the tapes, but Watson appealed.
The LAPD has sought the tapes on the basis that they could provide clues to unsolved murders.
A message left for an LAPD spokesman was not immediately returned Tuesday.
Watson is serving a life sentence in California for his role in the 1969 murders of actress Sharon Tate and six others.
His attorney, Kelly Puls, declined immediate comment.