Lumbar spine stenosis represents a complex degenerative pathology that has been a subject of significant dispute when it comes to fusion. A review of the literature from 2008 to 2019 was performed on the role of fusion in the treatment of lumbar spinal stenosis using PubMed, Ovid Medline, Cochrane Central Register of Controlled Trials, and the Cochrane Database of Systematic Reviews. Using the key words “lumbar spinal stenosis,” “lumbar fusion,” “lumbar decompression,” and “lumbar pedicle screw fixation,” the search revealed 490 papers. Of these, only Level 1 or Level 2 evidence papers were selected, leading to only 3 randomized controlled trials (RCTs) that were analyzed. None of the good-quality studies (RCTs) performed so far have proven any clinical benefit of adding fusion to degenerative lumbar spine decompression. The effect of spinal instability on the outcome following decompression remains controversial. At present, no unanimous criteria exist among the RCTs to identify what constitutes true instability. Fusion for instability or stenosis alone remains controversial, and the results are unconvincing. At this point, the issue expands to not only lumbar degenerative diseases but spinal fractures and lumbar isthmic spondylolisthesis. We thereby present the consensus of the World Federation of Neurosurgical Societies Spine Committee, which formulated the indications for lumbar spine fusion in degenerative lumbar stenosis.