"The Defenders" realistically portrayed issues of the day, often in a court room setting. They produced the show in New York City with, if memory serves, location exteriors. The court room scenes were well written and directed, usually the high point of each program.
At its best, the acting could be very good indeed. E.G. Marshall and Robert Reed worked well together as father and son attorneys. Their roles in this series provided them with career high points. The guest stars added further strength to the show.
As a teenager then, I thought it was a cutting edge show. It would probably be dated if viewed today, since it was filmed mostly in black and white (though the last season might have been color), and production values were different then. One of the best shows of its era, it should be released on DVD, but probably won't be because of onerous residuals obligations.