Absolutely wrong. The Founders came from the same kind of adversarial legal system we have today, a system that predates the Constitution. It's likely the Founders would have found the lack of ethics among some lawyers abhorrent, but they came from an adversarial system and enshrined it in the Constitution because it is the best system invented so far.
Your words: "Absolutely wrong. The Founders came from the same kind of adversarial legal system we have today, a system that predates the Constitution."
You missed my point. Of course, the Founders advocated an adversarial system as the best protection for liberty. The key clause in my statement was: "today's defense lawyers believe it to be their constitutional duty to help guilty persons avoid the consequences of their acts." It is that aspect of today's system, I believe, that the Founders would find disturbing and opposing their concept of justice.
Quote for me any one of the Founders who believed that justice demanded that a defense attorney should assist in freeing a guilty person.
While even a guilty person should be afforded counsel and rights to a jury trial before his/her peers, they believed, the Founders, IMHO, would never approve of the misuse and abuse of the adversarial system which is practiced today (witness the O. J. case and other equally bizarre miscarriages of justice).