Abstract: In this manuscript we report an evaluation of the reliability of clinical research rules creation by multiple clinicians using the Health Archetype Language (HAL-42) and user interface. HAL-42 is a language which allows real time epidemiological inquiry using automatically derived clinical encodings with any health Ontology. This evaluation used SNOMED CT as the underlying Ontology. The inquiries were performed on a population of 17,731 patients whose 50,000 clinical records have all been fully encoded in SNOMED CT. Four subject matter experts (SMEs) were asked independently to encode and run 10 rules/studies. The inter-rater agreement was 74.8{ca7ad0b74511a57bb2016f24c729dd7716d5352e92d2275aa1f91fb22c36b0a7} (p=0.6526) with a Kappa statistic of 0.49217 (p=0.5722). The ten rules were divided into three easy rules, four moderate and three compl….