The Transportation Security Administration (TSA) has started charging travelers without REAL ID a $45 fee to fly, but a regulatory expert claims this fee is illegal as there is no US law requiring ID to fly domestically. The REAL-ID Act only pertains to which IDs are accepted by federal agencies, not to imposing a new ID requirement for airline passengers. The expert argues that exercising the right to fly without ID is difficult due to potential arrests and legal challenges. The TSA's demand for ID and the $45 fee may be unconstitutional and has not been approved by the Office of Management and Budget.