Mark also attended the Capital Defense College, at the Santa Clara University School of Law. He was the only private lawyer to submit proposed trial and penalty phase jury instructions to be considered by Criminal Jury Instruction Committee for inclusion in the "pattern" jury instructions under the new statute. He was also was called upon by the newly formed Capital Defender Office to write a chapter for its manual on the jury selection process in death penalty cases. The resulting work, for which he teamed up with his friend Rosalyn Lindner, Ph.D., one of the original members of the National Jury Project, was later incorporated into a revision of California's Death Penalty Defense Manual by Dorothy Bischoff and John Philipsborn.

Mark also authored a series of papers on the critical issue of fees for capital defense. The recommendations therein were nearly exactly followed when the rates were finally approved by the New York Court of Appeals. They were the highest rates in the nation, and the only fee schedule expressly approving rates of compensation for associates and paralegals and clerks in the firms of the appointed attorneys.

When Governor Pataki balked at allowing the payments for associates and paralegals, which was a critical part of Mark's proposal, we sued the governor. After four years of litigation we prevailed in a unanimous decision against the Governor in, Mahoney v. Pataki, 98 N.Y.2d 45 (2002).

Mark was appointed to defend the very first case that was scheduled for trial under the new statute, in the double homicide case of People v. Grinnell, in Batavia, NY. However that case was settled without trial when the state finally agreed to a life sentence.

Jim Harrington has been appointed to numerous cases involving the potential for the death penalty. In People v. Jonathan Parker, a case involving the murder of a police officer, he defended the only death penalty case to actually go to trial in Buffalo, successfully avoiding the death penalty for his client.

Even though there is currently a hiatus in the enforcement of the death penalty in New York, because of rulings by the Court of Appeals, Jim has continued his efforts in the defense of capital cases. At the request of the Georgia Resource center he is handling a state habeas corpus proceeding for a Georgia death row inmate, and he teaches a course on the death penalty at the State University of New York at Buffalo Law School.