This article presents the current science regarding the causation for herniated lumbar discs, taken from the second edition of the AMA Guides to the Evaluation of Disease and Injury Causation. Sciatica is a relatively common disorder; point prevalence population estimates range from 2% to 5%. People with sciatica may or may not have lumbar disc herniations (lumbar herniated nucleus pulposus). Sciatica is described by a variety of terms, including radiculopathy, lumbosacral radicular syndrome, and nerve root irritation. Different definitions of sciatica have been used in epidemiologic surveys, and studies concerning sciatic pain or sciatica generally have used self-reported risk factors in a cross-sectional design—these studies have drawn contradictory conclusions regarding the risk factors associated with lumber radiculopathy. Insufficient scientific evidence exists to justify attributing the cause of lumbar disc herniation to any minor trauma event or ergonomic risk factor; supposed “post hoc ergo propter hoc” (after this, therefore because of this) associations show only association, not causation. The article includes several tables, including risk factors for lumbar disc herniation, risk factors for sciatica, and a summary of evidence for low back pain.