However, it's worth noting that most airlines have some kind of dress code. In fact, as written, Delta's rules aren't that different from United's. The airline's Contract of Carriage says it won't let you board if you're barefoot or have "a malodorous condition." It also lists vague but stricter conditions for dress with its Buddy Pass Rider system, the Delta equivalent of what the three girls in leggings were traveling with United.
Following leggings-gate, United tweeted out its Contract of Carriage and cited Rule 21 and the portion that says it can refuse service to passengers "who are barefoot or not properly clothed." Though, United later stepped that back a bit to specifically point to the pass rider guidelines.
“When taking advantage of this benefit, all employees and pass riders are considered representatives of United," the statement read. "And like most companies, we have a dress code that we ask employees and pass riders to follow. To our regular customers, your leggings are welcome.”