Upvote:3
Most countries can hold the airlines responsible to carry passengers back if they carry a passenger without a valid documentation. That's why airlines checks for travel documents and may refuse you from boarding if they have a good reason to believe that you will be refused entry or have other problems. Whether the airline staffs' assessment of your situation is accurate or not really depends on what you tell them about your travel plan and how you can convince them that your papers are actually in order or will be so, and won't cause a problem for them.
As for "legality" of refusing service, I am not a lawyer (and laws relating to international travels are always confusing because of the multiple jurisdictions involved), but I believe since an aircraft is pretty much a private business establishment, they pretty much have the right to refuse anyone for any purpose (except if the refusal is solely based on protected statuses as defined by anti-discrimination law, which includes: race, color, religion, national origin, and sometimes sexual orientation).
Upvote:8
I am not a lawyer or an immigration expert, but if your mother was, in essence, visiting the US once on the way out and then not visiting it on the way back, it is irrelevant whether her Visa Waiver would have expired (ESTA is not a visa - it is merely a certification that allows her to board a plane - the Visa Waiver is what permits her to enter the US, and they generally permit a stay of 90 days).
There are other requirements for ESTA/VWP travel, such as having a machine-readable passport. You will need to make sure Mom has complied with all of them.
There is a different issue that 6 months is a long time to stay in Canada as a tourist, but if the airline were concerned about that they would not have allowed her to board a flight to Toronto
From what you say it looks very much to me as if the airline made a mistake. Talk to their customer service department, and make sure you point out that your Mom was not visiting the US on her way back.
In general it is certainly legal that an airline can deny boarding if they believe the passenger would be denied entry when they arrive, and it happens all the time.
(All of the above assumes that your mother is a Slovakian citizen)
EDIT: In response to the additional edit to the question, I recommend that you write back to Austrian Airlines stating clearly that you believe that your mother had the necessary paperwork to complete the flight, and that you believe the airline made a mistake in denying her boarding. Ask them how to make a formal complaint.
Upvote:8
OP writes:
If she had an approved ESTA, she would be able to travel to the US. Please contact the airlines
They wrote:
We were very sorry to hear about your regrettable experience in Vienna. While we are unable to explain why you were not accepted on your original flight , we can certainly understand your disappointment and truly regret the inconveniences as described.
They are about to pay mom's expenses.