the same designs can be used in different fields where there is no risk of confusing similar sources. To give up control of a trademark would result in the loss of that trademark. Therefore, no open-source license freely offers the use of a trademark.

Trademark restrictions can overlap copyrights and affect material otherwise freely available. The US Supreme Court described using trademark law to restrict public domain content as "mutant copyright". In Dastar Corp. v. Twentieth Century Fox Film Corp.,