Why do airlines have the power to kick passengers off planes?
Passengers being ejected from flights has become more common in the news lately.
In April, for example, Khairuldeen Makhzoomi was removed from a plane for talking to his uncle on the phone in Arabic.
See also: Student removed from plane for speaking Arabic
See also: Easyjet passenger forced off London plane for looking 'suspicious'
But what is it that gives airlines the right and powers to throw people off planes?
The fact is that every time someone buys an airline ticket, they sign a 'contract of carriage'.
This is a document with more than 40 pages that is in the terms and conditions that all passengers have to agree to when they book their flight.
For example, Southwest Airlines in the USA can chuck any passenger off the plane who they determine to be disorderly, abusive, threatening, intimidating or violent.
Some airlines even have the power to throw passengers off for smelling bad!
Airlines give themselves a lot of power over who to throw off but flight attendant, Heather Poole, said she's seen many passengers remain on flights when they definitely should have been made to leave.
In 2015 alone there were 99 passengers who were removed and fined for their behaviour on board. In 2016 so far there have only been 9 such cases.
Just last weekend a man was taken off an American Airlines flight after a female passenger saw him working on a maths equation and told flight staff.
Guido Menzio showed agents at Philadelphia Airport what he was working on and the flight then took off with a two hour delay.
Writing on Facebook he explained that his fellow passenger had thought he was a terrorist because he was 'writing strange things on a pad of paper'. Menzio was later determined not to be a 'credible threat'.