Monte Markham took over the role of Perry Mason from Raymond Burr. Burr would later reprise the role, starting with the 1985 TV movie "Perry Mason Returns".
The prolific author and creator of Perry Mason Erle Stanley Gardner had died in 1970 so he could not oversee and supervise this version of his famous character as he did the original TV series. Gardner was extremely protective of his creation during the Raymond Burr years and even then was unhappy with many of the scripts that he had to approve. He would have hated this version of Perry Mason as he did the movies Warner's made in the 1930s. When Ricardo Cortez took over the role Gardner highly objected to his portrayal.