A gag rule may be formally neutral, that is, forbidding discussions or arguments either for or against a particular policy.
For example, William Laud, the Archbishop of Canterbury during the reign of King Charles I of England:forbade ministers to discuss the sublime mysteries associated with Calvin's doctrine of predestination.
They could not mention it at all ... For Laud, what was at stake was not so much the promotion of his own theological opinions as the suppression of the furor theologicus that had caused so much devastation in England and throughout Europe in the aftermath of the Reformation.
[1]However, in practice, the effect (and in most cases, the intent) of even an even-handed ban on advocating or opposing a particular policy will be to entrench the status quo.
A present-day example can be found in the Dewan Negara (Senate) of Malaysia, which has a standing order prohibiting any member from proposing the repeal of those articles of the Malaysian Constitution that reserve certain privileges for Bumiputra (such as ethnic Malay) citizens and questioning the status of Bahasa Malaysia as the national language.