Jonathan Mark Weiss

Mark passed away peacefully on April 9, 2026, at home in Port Townsend, in the place he loved, and with his wife Teresa by his side. He was 66. The cause was pancreatic cancer. Mark had lived a full life—curious, principled, and quietly devoted to the idea that even the hardest moments in a family's life could be handled with dignity.

Mark worked his way through college, managed movie theaters for a couple of years, and eventually found his way to the law. He joined Ferguson & Burdell in Seattle in 1987, focusing on general civil practice before striking out on his own and earning a reputation as one of the better family law attorneys in Washington State. The accolades followed: “Attorney of the Year” from the WSBA Family Law Section, chair of the Family Law Executive Committee, appointments to committees that drafted court rules and legislation, invitations to teach in dozens of continuing education courses, and articles in professional journals. But those achievements only tell part of the story. He believed deeply that families going through divorce deserved care, respect, and a better process than the one often provided.

In 2007, Mark made a choice that reflected that belief. He stepped away from traditional family law and became one of the first practitioners of Collaborative Law in Washington. It was a different way of helping families—one that focused on resolving conflict without causing further harm. He was good at it and spent the rest of his career advancing his skills. He trained other professionals—lawyers, financial advisors, and mental health professionals—in the basics of Collaborative Law and in dispute resolution methodologies. In 2013 he helped shepherd the Washington Uniform Collaborative Law Act into existence. From 2015 to 2017 he served as a lead drafter of the Ethical Standards for the International Academy of Collaborative Professionals. Shortly before the pandemic, he transitioned to become a full-time mediator, working with couples in their hardest moments and helping them find a way through. He retired in 2022, having spent a career focused on making divorces less adversarial and a little more humane.

Outside of work, Mark was a lifelong learner with many interests. He flew airplanes and taught others to fly. He bicycled, kayaked, and hiked. He practiced yoga and traveled whenever he could. He photographed the world around him and, in his later years, started drawing and painting it too. He read voraciously—not just in his own field but across psychology, parenting, finance, history, and whatever else pulled at him. He loved Baroque music and the time he spent with his dogs.

Mark is survived by his wife Teresa Sisk, mother Harriet, and sisters Deanne, Maureen, and Kerry. In lieu of flowers, the family asks that donations be made to the Jefferson Community Foundation at jcfgives.org.