diff --git a/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php b/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php
--- a/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php
+++ b/src/applications/subscriptions/controller/PhabricatorSubscriptionsEditController.php
@@ -47,15 +47,6 @@
         $handle->getURI());
     }
 
-    if (!PhabricatorPolicyFilter::canInteract($viewer, $object)) {
-      $lock = PhabricatorEditEngineLock::newForObject($viewer, $object);
-
-      $dialog = $this->newDialog()
-        ->addCancelButton($handle->getURI());
-
-      return $lock->willBlockUserInteractionWithDialog($dialog);
-    }
-
     if ($object instanceof PhabricatorApplicationTransactionInterface) {
       if ($is_add) {
         $xaction_value = array(
diff --git a/src/applications/subscriptions/events/PhabricatorSubscriptionsUIEventListener.php b/src/applications/subscriptions/events/PhabricatorSubscriptionsUIEventListener.php
--- a/src/applications/subscriptions/events/PhabricatorSubscriptionsUIEventListener.php
+++ b/src/applications/subscriptions/events/PhabricatorSubscriptionsUIEventListener.php
@@ -73,24 +73,20 @@
         ->setName(pht('Automatically Subscribed'))
         ->setIcon('fa-check-circle lightgreytext');
     } else {
-      $can_interact = PhabricatorPolicyFilter::canInteract($user, $object);
-
       if ($is_subscribed) {
         $sub_action = id(new PhabricatorActionView())
           ->setWorkflow(true)
           ->setRenderAsForm(true)
           ->setHref('/subscriptions/delete/'.$object->getPHID().'/')
           ->setName(pht('Unsubscribe'))
-          ->setIcon('fa-minus-circle')
-          ->setDisabled(!$can_interact);
+          ->setIcon('fa-minus-circle');
       } else {
         $sub_action = id(new PhabricatorActionView())
           ->setWorkflow(true)
           ->setRenderAsForm(true)
           ->setHref('/subscriptions/add/'.$object->getPHID().'/')
           ->setName(pht('Subscribe'))
-          ->setIcon('fa-plus-circle')
-          ->setDisabled(!$can_interact);
+          ->setIcon('fa-plus-circle');
       }
 
       if (!$user->isLoggedIn()) {
diff --git a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
--- a/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
+++ b/src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php
@@ -1648,9 +1648,48 @@
         // don't enforce it here.
         return null;
       case PhabricatorTransactions::TYPE_SUBSCRIBERS:
-        // TODO: Removing subscribers other than yourself should probably
-        // require CAN_EDIT permission. You can do this via the API but
-        // generally can not via the web interface.
+        // Anyone can subscribe to or unsubscribe from anything they can view,
+        // with no other permissions.
+
+        $old = array_fuse($xaction->getOldValue());
+        $new = array_fuse($xaction->getNewValue());
+
+        // To remove users other than yourself, you must be able to edit the
+        // object.
+        $rem = array_diff_key($old, $new);
+        foreach ($rem as $phid) {
+          if ($phid !== $this->getActingAsPHID()) {
+            return PhabricatorPolicyCapability::CAN_EDIT;
+          }
+        }
+
+        // To add users other than yourself, you must be able to interact.
+        // This allows "@mentioning" users to work as long as you can comment
+        // on objects.
+
+        // If you can edit, we return that policy instead so that you can
+        // override a soft lock and still make edits.
+
+        // TODO: This is a little bit hacky. We really want to be able to say
+        // "this requires either interact or edit", but there's currently no
+        // way to specify this kind of requirement.
+
+        $can_edit = PhabricatorPolicyFilter::hasCapability(
+          $this->getActor(),
+          $this->object,
+          PhabricatorPolicyCapability::CAN_EDIT);
+
+        $add = array_diff_key($new, $old);
+        foreach ($add as $phid) {
+          if ($phid !== $this->getActingAsPHID()) {
+            if ($can_edit) {
+              return PhabricatorPolicyCapability::CAN_EDIT;
+            } else {
+              return PhabricatorPolicyCapability::CAN_INTERACT;
+            }
+          }
+        }
+
         return null;
       case PhabricatorTransactions::TYPE_TOKEN:
         // TODO: This technically requires CAN_INTERACT, like comments.