Soil and geologic evidence has been examined in the FBI Laboratory since 1939, and long admitted into trials, both in the US and abroad. However, to the best our knowledge soil evidence did not undergo a formal admissibility challenge within the US court systems until 29^th January 2016. Forensic soil analysis is typically a comparison between two or more samples to see whether they originated from different sources. When soil samples are indistinguishable, the possibility that they originated from a single source cannot be eliminated. The challenge in State of Kansas v. Kyle Flack, 13CR104 (2016), involved the admissibility of soil comparisons at the trial, as well as the qualifications of the forensic geologist who conducted the examinations. The views expressed are those of the authors and do not necessarily reflect the official policy or position of the FBI. Names of commercial manufacturers are provided for identification purposes only, and inclusion does not imply endorsement of the manufacturer or its products or services by the FBI.