private function isProctored(TestSession $session)
    {
        //check only once
        if (is_null($this->isProctored)) {
            $this->isProctored = false;

            if (!is_null($session)) {
                $user = \common_session_SessionManager::getSession()->getUser();
                $deliveryExecution = ServiceProxy::singleton()->getDeliveryExecution($session->getSessionId());
                $this->isProctored = $this->getServiceManager()->get(TestTakerAuthorizationService::SERVICE_ID)->isProctored($deliveryExecution->getDelivery(), $user);
            }

        }
        return $this->isProctored;
    }