In my salad days, I towed a (discovered later) 2800# sailboat with a Toyota Crown with a hitch that said 1500# right on it. God protected me and I had no issues.
That being said, I have matured somewhat and now wouldn't tow over capacity for all the tea in China. A little web crawl will find interesting things:
What is the towing capacity of the Toyota Prius?
Toyota does not recommend towing with the Prius, so the factory does not provide any engineering data or specifications for towing.
That said, there are some light-duty hitches available through the aftermarket that will install on a Prius. They typically are not load-rated, as they were designed to carry add-on fixtures like a bicycle carrier.
[Here the article says things I don't agree with and don't want to expose anyone to, so I decided to delete it - RCH]
Don't even mention warranty coverage...it's not gonna happen."
What is the towing capacity of the Toyota Prius
Legally, what the car can do is not the issue. It is what the car is rated to do. If you have an accident, you can be sued big time, your insurance carrier can disown you for using your vehicle "not as intended by the manufacturer", and if someone is killed, you may face negligent homicide charges. Things can get ugly.
Proper Tow Vehicles A Must!