diff --git a/drafts/erikj_federation.rst b/drafts/erikj_federation.rst
index 094d63e5..c50eb54c 100644
--- a/drafts/erikj_federation.rst
+++ b/drafts/erikj_federation.rst
@@ -252,8 +252,14 @@ inform the other with suitable proof.
 The proofs can be:
 
 - An *event chain* that shows an auth event is *not* an ancestor of the event.
+  This can be done by giving the full ancestor chains up to the depth of the
+  invalid auth event.
 - Given an event (and event chain?) showing that authorization had been revoked.
 
+If a server discovers it cannot prove the other side is wrong, then it accepts
+that the other is correct; i.e. we always accept that the other side is correct
+unless we can prove otherwise.
+
 
 
 State Resolution