private function classifierExists($classifier)
    {
        if (strpos($classifier, '/') !== false) {
            $classifierArray = array_map('strtolower', explode('/', $classifier));
            $testArray = array_change_key_case($this->classifiers);

            // Remap classifiers list to lowercase before validation
            foreach ($testArray as $key => $values) {
                $testArray [$key] = array_map('strtolower', $values);
            }

            if (!array_key_exists($classifierArray[0], $testArray)) {
                throw new \Exception("Classifier namespace {$classifierArray[0]} does not exist in Classifiers list");
            }

            if (!in_array($classifierArray[1], $testArray[$classifierArray[0]])) {
                throw new \Exception("Classifier {$classifierArray[1]} does not exist in Classifiers list");
            }

            return array($classifierArray[0], $classifierArray[1]);
        }

        return false;
    }