Our suitcases were packed with excitement—suntan lotion, sunglasses, and anticipation filled the air as my family stood in line to board a luxurious cruise ship. We smiled big as we approached the security checkpoint, passports in hand. But then, a problem.

My cousin and her husband were held back. She had unknowingly brought an expired passport, thinking her diplomatic visa—which had worked countless times before—would be sufficient.

“Sorry,” the agent said, “without a valid passport or b...