If I understand US trademark law, if you are using a Trademark in business, it can not be copied even if it is not registered. Whoever uses it first has a de facto trademark in effect. Is that correct?
Obviously registration of a trademark provides proof of the trademark, but that is not sufficient. For a trademark to be valid, it has to be used. That is why trademark registrations have to be renewed and will lapse if not. But is use of a trademark alone sufficient?