diff --git a/bugpattern/TraditionalSwitchExpression.md b/bugpattern/TraditionalSwitchExpression.md
index 922f909b4bf..2b70f0c5531 100644
--- a/bugpattern/TraditionalSwitchExpression.md
+++ b/bugpattern/TraditionalSwitchExpression.md
@@ -12,6 +12,13 @@ To make changes, edit the @BugPattern annotation or the explanation in docs/bugp
 -->
 
 
+## The problem
+The newer arrow (`->`) syntax for switches is preferred to the older colon (`:`)
+syntax. The main reason for continuing to use the colon syntax in switch
+*statements* is that it allows fall-through from one statement group to the
+next. But in a switch *expression*, fall-through would only be useful if the
+code that falls through has side effects. Burying side effects inside a switch
+expression makes code hard to understand.
 
 ## Suppression
 Suppress false positives by adding the suppression annotation `@SuppressWarnings("TraditionalSwitchExpression")` to the enclosing element.