diff --git a/changelog.d/6502.removal b/changelog.d/6502.removal
new file mode 100644
index 000000000000..0b72261d58b1
--- /dev/null
+++ b/changelog.d/6502.removal
@@ -0,0 +1 @@
+Remove redundant code from event authorisation implementation.
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index ec3243b27bee..c940b8447080 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -42,6 +42,8 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
     Returns:
          if the auth checks pass.
     """
+    assert isinstance(auth_events, dict)
+
     if do_size_check:
         _check_size_limits(event)
 
@@ -74,12 +76,6 @@ def check(room_version, event, auth_events, do_sig_check=True, do_size_check=Tru
             if not event.signatures.get(event_id_domain):
                 raise AuthError(403, "Event not signed by sending server")
 
-    if auth_events is None:
-        # Oh, we don't know what the state of the room was, so we
-        # are trusting that this is allowed (at least for now)
-        logger.warning("Trusting event: %s", event.event_id)
-        return
-
     if event.type == EventTypes.Create:
         sender_domain = get_domain_from_id(event.sender)
         room_id_domain = get_domain_from_id(event.room_id)