diff --git a/.spectral.yaml b/.spectral.yaml
index a64686716..53849f2e8 100644
--- a/.spectral.yaml
+++ b/.spectral.yaml
@@ -156,6 +156,17 @@ rules:
         functionOptions:
           match: "^(dev|qa|stage|prod)(,(dev|qa|stage|prod))*$"
 
+  no-slash-before-custom-method:
+  description: "Custom methods (e.g., ':applyItem') should not be preceded by a '/'."
+  message: "The path '{{path}}' contains a '/' before a custom method. Custom methods should not start with a '/'."
+  severity: error
+  given: "$.paths"
+  then:
+    field: "@key"
+    function: pattern
+    functionOptions:
+      notMatch: "/[^/]+/:[a-zA-Z]+$"
+
 overrides:
   - files: # load sample data has an issue with different path param names for different VERBS
       - "*.yaml#/paths/~1api~1atlas~1v1.0~1groups~1%7BgroupId%7D~1sampleDatasetLoad~1%7BsampleDatasetId%7D"