Palin who ran for the office of the US vice-president, had applied to trademark her as well as her daughter Bristol Palin's name for "motivational speaking services".
However the application was refused due to the absence of a signature. "Registration is refused because the applied-for mark, SARAH PALIN, consists of a name identifying a particular living individual whose consent to register the mark is not of record," the patent agency said in an office action, reported Reuters.
However the application can be reconsidered if it comes back with valid signatures of Palin and her daughter.
Trademarking is a common practice among celebrities in the US who try to promote their names as brands. In Palin's case it is unusual because politicians do not generally associate their names with commercial endorsements.
Palin, a popular figure among the US public, seeks to trademark her name in relation with "providing motivational speaking services in the field of politics, culture, business and values."