In college, he was a Ford Foundation-funded Congressional Intern in Washington, D.C., in the office of US Representative Samuel S. Stratton, and studied governmental affairs.

After graduation from Union College, Weinstein spent three summers working as a chemist at Woods Hole Marine Biological Laboratory.

He researched the potential sources of toxic chronic chemical injury, from trace amounts of rocket propellants and oxidizers, to airmen working in Titan missile silo environments.

[8][9][10] In 1975, Weinstein was named the Harriet Blair Borland Professor and chairman of pathology at Rush Medical College in Chicago.

[19] While a department chair at Rush Medical College in Chicago, Weinstein carried out the first public demonstration of satellite-enabled robotic telepathology, between El Paso, TX.

[21][22] He established an international telepathology service network linking the United States, Mexico and China.

[23][24] Weinstein has been referred to as the “father of telepathology” in a 2011 journal article written by a student and a faculty member from an Indian medical school.

[27] The ATP links 160 sites in 70 communities by broadband telecommunications and has provided telemedicine services for 1.4 million cases in 61 subspecialties of medicine.

The ATP includes: the Tucson-based Warren Street Clinic, a dual-purpose clinical education facility which provides real-time tele-medicine specialty services across the network and hands-on training for participants in the ATP's regularly scheduled full day telemedicine courses;[28] the T-Health Amphitheater, a video conferencing center located at the T-Health Institute on the Phoenix Biomedical Campus is in downtown Phoenix;[29] and the federally-funded Southwest Telehealth Resource Center, which provides technical support and staff training for telehealth programs in the southwestern United States.

[42] Global health Weinstein was involved in the creation and evaluation of multi-national telemedicine and telepathology programs.

[45] The T-Health Amphitheater, in Phoenix, AZ, a "Classroom-of-the-Future" co-designed by Weinstein, received the 21st Century Achievement Award, Education and Academia category, from the International Computer World Honors program.

[46] In 1982, Weinstein, and his sister and business partner, Beth Newburger, co-founded OWLCAT, Inc., an early entrant in the IBM computer-based, S.A.T.