diff --git a/commerce_services.module b/commerce_services.module
index e9f606f..d05627d 100644
--- a/commerce_services.module
+++ b/commerce_services.module
@@ -5,6 +5,25 @@
  * Defines Services resources for Drupal Commerce entities and systems.
  */
 
+/**
+ * Implements hook_permission().
+ */
+function commerce_services_permission() {
+  return array(
+    'use line-item/retrieve method' => array(
+      'title' => t("Use 'retrieve' method of 'line-item' resource."),
+    ),
+    'use line-item/create method' => array(
+      'title' => t("Use 'create' method of 'line-item' resource."),
+    ),
+    'use line-item/update method' => array(
+      'title' => t("Use 'update' method of 'line-item' resource."),
+    ),
+    'use line-item/delete method' => array(
+      'title' => t("Use 'delete' method of 'line-item' resource."),
+    ),
+  );
+}
 
 /**
  * Implements hook_services_resources().
@@ -1441,7 +1460,7 @@ function commerce_services_update_field_value($entity_type, $entity, $field_info
   // was not zero, so we ensure this is the case by changing the delta key of
   // the field value array.
   if ($field_info['cardinality'] == 1) {
-    $current_delta = key($entity->{$field_name}[$langcode]);
+    $current_delta = isset($entity->{$field_name}[$langcode]) ? key($entity->{$field_name}[$langcode]) : 0;
 
     if ($current_delta != 0) {
       $entity->{$field_name}[$langcode][0] = $entity->{$field_name}[$langcode][$current_delta];
diff --git a/resources/line_item.inc b/resources/line_item.inc
index e4770ea..959e428 100644
--- a/resources/line_item.inc
+++ b/resources/line_item.inc
@@ -48,8 +48,11 @@ function commerce_services_line_item_retrieve_access($line_item_id) {
   // Attempt to load the line item.
   if ($line_item = commerce_line_item_load($line_item_id)) {
     // And perform the view access check.
-    if (commerce_line_item_access('view', $line_item)) {
-      return TRUE;
+    global $user;
+    if (user_access('use line-item/retrieve method') || commerce_line_item_access('view', $line_item)) {
+      if ($user->uid == $order->uid) {
+        return TRUE;
+      }
     }
     else {
       return services_error(t('Access to this operation not granted'), 401);
@@ -144,8 +147,11 @@ function commerce_services_line_item_create_access($data) {
   }
 
   // If the user has access to update the order...
-  if (commerce_order_access('update', $order)) {
-    return TRUE;
+  global $user;
+  if (user_access('use line-item/create method') || commerce_order_access('update', $order)) {
+    if ($user->uid == $order->uid) {
+      return TRUE;
+    }
   }
   else {
     return services_error(t('Access to this operation not granted'), 401);
@@ -226,8 +232,11 @@ function commerce_services_line_item_update_access($line_item_id) {
   // Attempt to load the line item.
   if ($line_item = commerce_line_item_load($line_item_id)) {
     // If the user has access to perform the operation...
-    if (commerce_line_item_access('update', $line_item)) {
-      return TRUE;
+    global $user;
+    if (user_access('use line-item/update method') || commerce_line_item_access('update', $line_item)) {
+      if ($user->uid == $order->uid) {
+        return TRUE;
+      }
     }
     else {
       return services_error(t('Access to this operation not granted'), 401);
@@ -261,8 +270,11 @@ function commerce_services_line_item_delete_access($line_item_id) {
   // Attempt to load the line item.
   if ($line_item = commerce_line_item_load($line_item_id)) {
     // If the user has access to perform the operation...
-    if (commerce_line_item_access('delete', $line_item)) {
-      return TRUE;
+    global $user;
+    if (user_access('use line-item/delete method') || commerce_line_item_access('delete', $line_item)) {
+      if ($user->uid == $order->uid) {
+        return TRUE;
+      }
     }
     else {
       return services_error(t('Access to this operation not granted'), 401);