diff --git a/bigchaindb/utils.py b/bigchaindb/utils.py
index f87916b7..f339edbe 100644
--- a/bigchaindb/utils.py
+++ b/bigchaindb/utils.py
@@ -114,15 +114,9 @@ def condition_details_has_owner(condition_details, owner):
 
 
 def output_has_owner(output, owner):
-    # TODO
-    # Check whether it is really necessary to treat the single key case
-    # differently from the multiple keys case, and why not just use the same
-    # function for both cases.
-    if len(output['public_keys']) > 1:
+    if len(output['public_keys']) > 0:
         return condition_details_has_owner(
             output['condition']['details'], owner)
-    elif len(output['public_keys']) == 1:
-        return output['condition']['details']['public_key'] == owner
     # TODO raise proper exception, e.g. invalid tx payload?