Generally, a business cannot stop you from posting a bad review online. If you buy something from a seller, the sales contract cannot include anything that says you are not allowed to make any statements about the seller, employees, or the items you bought. This includes any services you pay for. A contract that has terms that try to keep you from leaving reviews cannot be enforced.
It is also against the law for a business to punish you if you had a bad experience and posted a negative review online. However, it is not against the law for a business that hosts a website for reviews to remove them.
Updated: February 2018