An assignment in gross is not valid. Worse, it will cause the trademark to be deemed abandoned. This means the assignee does not acquire trademark rights and the assignor (trademark owner) loses them. The priority date of the trademark is also lost. These are drastic consequences. They are deemed necessary to prevent consumer confusion. The assignment in gross doctrine helps ensure that a trademark, serving as a source identifier, continues to represent the same goods or services with which consumers associate it.
What this means is that to have a valid trademark assignment, the trademark must be assigned along with other brand assets and the assignee must produce substantially similar goods or services to the ones the assignor marketed under the trademark. If, for example, Sony sells its trademark to Eddie Johnson and Eddie proceeds to use the trademark SONY to market street tacos that he cooks up in his RV in his spare time, the transfer would be an invalid assignment in gross. This is because the goodwill associated with Sony electronic products does not carry over to street tacos. The assignee must use the trademark on substantially similar goods or services for the transfer to be valid.