diff --git a/config/gitlint/bad_signedoffby.py b/config/gitlint/bad_signedoffby.py
new file mode 100644
index 0000000..83a8eae
--- /dev/null
+++ b/config/gitlint/bad_signedoffby.py
@@ -0,0 +1,40 @@
+import re
+
+from gitlint.rules import CommitRule, RuleViolation
+
+
+class BadSignedOffBy(CommitRule):
+    name = "bad-signed-off-by"
+    id = "UC3"
+
+    # These are individuals, by email address, who chose to go by a one-word name.
+    exceptions = ["anthonyhkf@google.com"]
+
+    def validate(self, commit):
+        violations = []
+
+        sobs = [
+            x for x in commit.message.body if x.startswith("Signed-off-by:")
+        ]
+        for sob in sobs:
+            match = re.search("Signed-off-by: (.*) <(.*)>", sob)
+            if not match:
+                violations.append(
+                    RuleViolation(self.id, "Invalid Signed-off-by format", sob)
+                )
+                continue
+
+            if (
+                len(match.group(1).split()) <= 1
+                and match.group(2) not in self.exceptions
+            ):
+                violations.append(
+                    RuleViolation(
+                        self.id,
+                        "Signed-off-by user has too few words; likely user id instead of legal name?",
+                        sob,
+                    )
+                )
+                continue
+
+        return violations