Yes, airlines have the legal right to change your seat without notice at any time, as your ticket guarantees a journey from A to B, not a specific coordinate on the plane. According to 2026 DOT guidelines, these "involuntary seat reassignments" usually occur for operational safety (weight and balance), aircraft swaps, or to accommodate passengers with disabilities. For example, if a plane is changed to a model with a different seat map, the system automatically "shuffles" passengers, often separating groups. Another frequent cause is the "Family Seating" mandate; an airline may move you to ensure a child can sit next to their parent. While most airlines attempt to notify you via their app, they are not legally required to provide a refund for a "paid seat selection" unless they fail to provide a seat of "equivalent or greater value" in the new configuration.