diff --git a/smithy-model/src/main/java/software/amazon/smithy/model/validation/suppressions/ModelBasedEventDecorator.java b/smithy-model/src/main/java/software/amazon/smithy/model/validation/suppressions/ModelBasedEventDecorator.java
index a90ce944c28..889451ff635 100644
--- a/smithy-model/src/main/java/software/amazon/smithy/model/validation/suppressions/ModelBasedEventDecorator.java
+++ b/smithy-model/src/main/java/software/amazon/smithy/model/validation/suppressions/ModelBasedEventDecorator.java
@@ -151,6 +151,11 @@ private static ValidationEvent modifyEventSeverity(
             List<Suppression> suppressions,
             List<SeverityOverride> severityOverrides
     ) {
+        // ERROR and SUPPRESSED events cannot be suppressed.
+        if (!event.getSeverity().canSuppress()) {
+            return event;
+        }
+
         // Use a suppress trait if present.
         if (event.getShapeId().isPresent()) {
             ShapeId target = event.getShapeId().get();
diff --git a/smithy-model/src/test/java/software/amazon/smithy/model/knowledge/PropertyBindingIndexTest.java b/smithy-model/src/test/java/software/amazon/smithy/model/knowledge/PropertyBindingIndexTest.java
index b51c20ac8a6..c707142bc41 100644
--- a/smithy-model/src/test/java/software/amazon/smithy/model/knowledge/PropertyBindingIndexTest.java
+++ b/smithy-model/src/test/java/software/amazon/smithy/model/knowledge/PropertyBindingIndexTest.java
@@ -15,20 +15,18 @@
 
 package software.amazon.smithy.model.knowledge;
 
-import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.hasSize;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import software.amazon.smithy.model.Model;
 import software.amazon.smithy.model.shapes.MemberShape;
 import software.amazon.smithy.model.shapes.OperationShape;
 import software.amazon.smithy.model.shapes.ShapeId;
-import software.amazon.smithy.model.validation.Severity;
 import software.amazon.smithy.model.validation.ValidatedResult;
+import software.amazon.smithy.model.validation.ValidatedResultException;
 
 public class PropertyBindingIndexTest {
 
@@ -71,8 +69,6 @@ public void testIndex() {
         assertTrue(index.doesMemberShapeRequireProperty(model.expectShape(
                 ShapeId.from("com.example#ChangeResourceOutput$id"), MemberShape.class)));
 
-        assertThat(vrmodel.getValidationEvents(Severity.SUPPRESSED), hasSize(1));
-        assertThat(vrmodel.getValidationEvents(Severity.SUPPRESSED).get(0).getId(),
-                   equalTo("ResourceOperationInputOutput"));
+        Assertions.assertThrows(ValidatedResultException.class, () -> vrmodel.unwrap());
     }
 }
diff --git a/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-metadata-cannot-suppress-errors.errors b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-metadata-cannot-suppress-errors.errors
new file mode 100644
index 00000000000..2065c6e952a
--- /dev/null
+++ b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-metadata-cannot-suppress-errors.errors
@@ -0,0 +1 @@
+[ERROR] foo.baz#MyString: Trait `idempotent` | TraitTarget
diff --git a/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-metadata-cannot-suppress-errors.smithy b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-metadata-cannot-suppress-errors.smithy
new file mode 100644
index 00000000000..8bc35a09149
--- /dev/null
+++ b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-metadata-cannot-suppress-errors.smithy
@@ -0,0 +1,13 @@
+$version: "2"
+
+metadata suppressions = [
+    {
+        namespace: "foo.baz"
+        id: "TraitTarget"
+    }
+]
+
+namespace foo.baz
+
+@idempotent // < this is invalid
+string MyString
diff --git a/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-trait-cannot-suppress-errors.errors b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-trait-cannot-suppress-errors.errors
new file mode 100644
index 00000000000..2065c6e952a
--- /dev/null
+++ b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-trait-cannot-suppress-errors.errors
@@ -0,0 +1 @@
+[ERROR] foo.baz#MyString: Trait `idempotent` | TraitTarget
diff --git a/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-trait-cannot-suppress-errors.smithy b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-trait-cannot-suppress-errors.smithy
new file mode 100644
index 00000000000..195f18366b7
--- /dev/null
+++ b/smithy-model/src/test/resources/software/amazon/smithy/model/errorfiles/loader/suppression-trait-cannot-suppress-errors.smithy
@@ -0,0 +1,7 @@
+$version: "2"
+
+namespace foo.baz
+
+@suppress(["TraitTarget"])
+@idempotent // < this is invalid
+string MyString
diff --git a/smithy-model/src/test/resources/software/amazon/smithy/model/knowledge/member-property-index.smithy b/smithy-model/src/test/resources/software/amazon/smithy/model/knowledge/member-property-index.smithy
index 57287636421..2c9860a95ee 100644
--- a/smithy-model/src/test/resources/software/amazon/smithy/model/knowledge/member-property-index.smithy
+++ b/smithy-model/src/test/resources/software/amazon/smithy/model/knowledge/member-property-index.smithy
@@ -1,12 +1,5 @@
 $version: "2.0"
 
-metadata suppressions = [
-    {
-        id: "ResourceOperationInputOutput",
-        namespace: "com.example"
-    }
-]
-
 namespace com.example
 
 resource Resource1 {