He is a member of the Council of State Governments and serves on the Health and Human Services Committee of the Midwestern Legislative Conference of the CSG.
In 2023, Mathern was the only democrat in the North Dakota Senate to vote for a bill which would criminalize all abortions which occur after six weeks of gestation, with no exceptions for rape or incest.
[1][2] Mathern has been an active member of many organizations including Fargo-Cass County Economic Development Corporation, Catholic Charities of North Dakota, Bush Foundation of ND, SD, and MN, Prairie Roots Food Cooperative, PrairieRoots Community Fund, and Indigenous Association Fargo, ND.
He is the legislative appointee to the University of North Dakota School of Medicine and Health Sciences in Grand Forks ND.
In addition to his legislative duties, Senator Mathern is public policy director for Prairie St. John's, a behavioral healthcare organization.