Index: wp-admin/admin-ajax.php
===================================================================
--- wp-admin/admin-ajax.php	(revision 16991)
+++ wp-admin/admin-ajax.php	(working copy)
@@ -61,7 +61,9 @@
 	if ( ! $wp_list_table )
 		die( '0' );
 
-	$wp_list_table->check_permissions();
+	if ( ! $wp_list_table->ajax_user_can() )
+		die( '-1' );
+
 	$wp_list_table->ajax_response();
 
 	die( '0' );
@@ -1200,12 +1202,18 @@
 case 'inline-save-tax':
 	check_ajax_referer( 'taxinlineeditnonce', '_inline_edit' );
 
-	set_current_screen( 'edit-' . $_POST['taxonomy'] );
+	$taxonomy = sanitize_key( $_POST['taxonomy'] );
+	$tax = get_taxonomy( $taxonomy );
+	if ( ! $tax )
+		die( '0' );
 
+	if ( ! current_user_can( $tax->cap->edit_terms ) )
+		die( '-1' );
+
+	set_current_screen( 'edit-' . $taxonomy );
+
 	$wp_list_table = get_list_table('WP_Terms_List_Table');
 
-	$wp_list_table->check_permissions('edit');
-
 	if ( ! isset($_POST['tax_ID']) || ! ( $id = (int) $_POST['tax_ID'] ) )
 		die(-1);
 
Index: wp-admin/includes/class-wp-ms-sites-list-table.php
===================================================================
--- wp-admin/includes/class-wp-ms-sites-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-ms-sites-list-table.php	(working copy)
@@ -14,9 +14,8 @@
 		) );
 	}
 
-	function check_permissions() {
-		if ( ! current_user_can( 'manage_sites' ) )
-			wp_die( __( 'You do not have permission to access this page.' ) );
+	function ajax_user_can() {
+		return current_user_can( 'manage_sites' );
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-posts-list-table.php
===================================================================
--- wp-admin/includes/class-wp-posts-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-posts-list-table.php	(working copy)
@@ -78,11 +78,10 @@
 		) );
 	}
 
-	function check_permissions() {
+	function ajax_user_can() {
 		global $post_type_object;
 
-		if ( !current_user_can( $post_type_object->cap->edit_posts ) )
-			wp_die( __( 'Cheatin’ uh?' ) );
+		return current_user_can( $post_type_object->cap->edit_posts );
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-media-list-table.php
===================================================================
--- wp-admin/includes/class-wp-media-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-media-list-table.php	(working copy)
@@ -16,9 +16,8 @@
 		) );
 	}
 
-	function check_permissions() {
-		if ( !current_user_can('upload_files') )
-			wp_die( __( 'You do not have permission to upload files.' ) );
+	function ajax_user_can() {
+		return current_user_can('upload_files');
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-links-list-table.php
===================================================================
--- wp-admin/includes/class-wp-links-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-links-list-table.php	(working copy)
@@ -14,9 +14,8 @@
 		) );
 	}
 
-	function check_permissions() {
-		if ( ! current_user_can( 'manage_links' ) )
-			wp_die( __( 'You do not have sufficient permissions to edit the links for this site.' ) );
+	function ajax_user_can() {
+		return current_user_can( 'manage_links' );
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-terms-list-table.php
===================================================================
--- wp-admin/includes/class-wp-terms-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-terms-list-table.php	(working copy)
@@ -32,12 +32,10 @@
 		) );
 	}
 
-	function check_permissions( $type = '' ) {
+	function ajax_user_can() {
 		global $tax;
 
-		$cap = 'edit' == $type ? $tax->cap->edit_terms : $tax->cap->manage_terms;
-		if ( !current_user_can( $cap ) )
-			wp_die( __( 'Cheatin’ uh?' ) );
+		return current_user_can( $tax->cap->manage_terms );
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-users-list-table.php
===================================================================
--- wp-admin/includes/class-wp-users-list-table.php	(revision 16990)
+++ wp-admin/includes/class-wp-users-list-table.php	(working copy)
@@ -24,12 +24,11 @@
 		) );
 	}
 
-	function check_permissions() {
-		if ( ! $this->is_site_users && ! current_user_can( 'list_users' ) )
-			wp_die( __( 'Cheatin’ uh?' ) );
-
-		if ( $this->is_site_users && ! current_user_can( 'manage_sites' ) )
-			wp_die(__( 'You do not have sufficient permissions to edit this site.' ) );
+	function ajax_user_can() {
+		if ( $this->is_site_users )
+			return current_user_can( 'manage_sites' );
+		else
+			return current_user_can( 'list_users' );
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-list-table.php
===================================================================
--- wp-admin/includes/class-wp-list-table.php	(revision 16991)
+++ wp-admin/includes/class-wp-list-table.php	(working copy)
@@ -105,8 +105,8 @@
 	 * @since 3.1.0
 	 * @access public
 	 */
-	function check_permissions() {
-		die( 'function WP_List_Table::check_permissions() must be over-ridden in a sub-class.' );
+	function ajax_user_can() {
+		die( 'function WP_List_Table::ajax_user_can() must be over-ridden in a sub-class.' );
 	}
 
 	/**
Index: wp-admin/includes/class-wp-ms-themes-list-table.php
===================================================================
--- wp-admin/includes/class-wp-ms-themes-list-table.php	(revision 16990)
+++ wp-admin/includes/class-wp-ms-themes-list-table.php	(working copy)
@@ -36,16 +36,17 @@
 		) );
 	}
 
-	function check_permissions() {
+	function ajax_user_can() {
 		$menu_perms = get_site_option( 'menu_items', array() );
 
 		if ( empty( $menu_perms['themes'] ) && ! is_super_admin() )
-			wp_die( __( 'Cheatin’ uh?' ) );
+			return false;
 
 		if ( $this->is_site_themes && !current_user_can('manage_sites') )
-			wp_die( __( 'You do not have sufficient permissions to manage themes for this site.' ) );
+			return false;
 		elseif ( !$this->is_site_themes && !current_user_can('manage_network_themes') )
-			wp_die( __( 'You do not have sufficient permissions to manage network themes.' ) );
+			return false;
+		return true;
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-plugin-install-list-table.php
===================================================================
--- wp-admin/includes/class-wp-plugin-install-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-plugin-install-list-table.php	(working copy)
@@ -8,9 +8,8 @@
  */
 class WP_Plugin_Install_List_Table extends WP_List_Table {
 
-	function check_permissions() {
-		if ( ! current_user_can('install_plugins') )
-			wp_die(__('You do not have sufficient permissions to install plugins on this site.'));
+	function ajax_user_can() {
+		return current_user_can('install_plugins');
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-theme-install-list-table.php
===================================================================
--- wp-admin/includes/class-wp-theme-install-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-theme-install-list-table.php	(working copy)
@@ -8,9 +8,8 @@
  */
 class WP_Theme_Install_List_Table extends WP_List_Table {
 
-	function check_permissions() {
-		if ( ! current_user_can('install_themes') )
-			wp_die( __( 'You do not have sufficient permissions to install themes on this site.' ) );
+	function ajax_user_can() {
+		return current_user_can('install_themes');
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-ms-users-list-table.php
===================================================================
--- wp-admin/includes/class-wp-ms-users-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-ms-users-list-table.php	(working copy)
@@ -8,9 +8,8 @@
  */
 class WP_MS_Users_List_Table extends WP_List_Table {
 
-	function check_permissions() {
-		if ( ! current_user_can( 'manage_network_users' ) )
-			wp_die( __( 'You do not have permission to access this page.' ) );
+	function ajax_user_can() {
+		return current_user_can( 'manage_network_users' );
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-plugins-list-table.php
===================================================================
--- wp-admin/includes/class-wp-plugins-list-table.php	(revision 16990)
+++ wp-admin/includes/class-wp-plugins-list-table.php	(working copy)
@@ -27,16 +27,15 @@
 		) );
 	}
 
-	function check_permissions() {
+	function ajax_user_can() {
 		if ( is_multisite() ) {
 			$menu_perms = get_site_option( 'menu_items', array() );
 
 			if ( empty( $menu_perms['plugins'] ) && ! is_super_admin() )
-				wp_die( __( 'Cheatin’ uh?' ) );
+				return false;
 		}
 
-		if ( !current_user_can('activate_plugins') )
-			wp_die( __( 'You do not have sufficient permissions to manage plugins for this site.' ) );
+		return current_user_can('activate_plugins');
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-themes-list-table.php
===================================================================
--- wp-admin/includes/class-wp-themes-list-table.php	(revision 16990)
+++ wp-admin/includes/class-wp-themes-list-table.php	(working copy)
@@ -11,10 +11,9 @@
 	var $search = array();
 	var $features = array();
 
-	function check_permissions() {
+	function ajax_user_can() {
 		// Do not check edit_theme_options here. AJAX calls for available themes require switch_themes.
-		if ( !current_user_can('switch_themes') )
-			wp_die( __( 'Cheatin’ uh?' ) );
+		return current_user_can('switch_themes');
 	}
 
 	function prepare_items() {
Index: wp-admin/includes/class-wp-comments-list-table.php
===================================================================
--- wp-admin/includes/class-wp-comments-list-table.php	(revision 16977)
+++ wp-admin/includes/class-wp-comments-list-table.php	(working copy)
@@ -33,9 +33,8 @@
 		) );
 	}
 
-	function check_permissions() {
-		if ( !current_user_can('edit_posts') )
-			wp_die(__('Cheatin’ uh?'));
+	function ajax_user_can() {
+		return current_user_can('edit_posts');
 	}
 
 	function prepare_items() {