Case files for Third District Court (Salt Lake County) probate division primarily involve the probate of estates for deceased persons and guardianship for minors and persons who were deemed legally incompetent. Probate is judicial oversight of property in transition. Probate of estates is the process by which a deceased person's property is identified and maintained, his debts and taxes paid, and then remaining property distributed to beneficiaries as specified in a will or as required by law for persons who die intestate (without a will). In guardianship cases probate is the establishment of a guardian for minors or adults who were legally incompetent and hold property that needs management. In addition to probate these case files also include name changes and some adoptions.

Utah's Territorial Assembly established original jurisdiction over the probate of estates and the guardianship of persons who were deemed legally incompetent with county probate courts in 1852 (An Act in Relation to the Judiciary. Acts, Resolutions, and Memorials passed by the First Annual, and Special Sessions of the Legislative Assembly. Great Salt Lake City, 1852, Brigham H. Young, Printer. pp. 38-48). That jurisdiction transferred to the probate divisions of District Courts when County Probate Courts were abolished at statehood. This series includes cases handled by the Salt Lake County Probate Court during the Utah's territorial period, as well as those handled more recently by Third District Court (Salt Lake County). These case files include many prominent persons such as Brigham Young (case 553).

The probate process includes three parts. First, a petitioner must file with the court the documents necessary to have the court appoint a representative. Documents relating to this process include wills, petitions, letters of administration, bonds, etc., and a court order appointing an administrator, executor, or guardian. Second, the appointed representative does all that is necessary to manage the property through the period of transition. Documents filed here might include a court order appointing appraisers, notices to creditors, estate inventories, various kinds of financial statements, receipts, bills, and the court-appointed representative's final report. Finally, when all requirements have been met, such as all bills paid or a minor has become of age, the court mandates a final settlement and releases the representative from any further responsibility.

The Territorial Legislature made provision for formal adoptions in 1884 and assigned jurisdiction to County Probate Courts (Compiled Laws of Utah, vol. II, 1888, part 5, chapter 4). Adoption case files include a formal petition, documents supporting the petition and the court's final decree. In this series adoption case files begin in 1893. Whereas early adoptions were open to the public and sometimes published in the newspaper, adoptions later became private. Most adoption records in this series are closed to public access (see access restrictions note). In addition to probate and adoption, case files this series also include official name changes and a few cases involving conveyance of title filed near the turn of the century.