Apple banned Siri from saying the word "feminism" and designed the voice assistant to avoid the subject when asked direct questions about it.
The voice assistant, which is available on millions of iPhones, has been designed to circumvent any questions about feminism and point users to other sources of information rather than giving them an answer directly.
Apple decided to rewrite the way the app handles sensitive topics, allowing Siri to say it is in favour of equality but not feminism.
These parameters were last updated in June 2018 and advised developers to make sure Siri is "guarded when dealing with potentially controversial content", leaked documents seen by the Guardian state.
A former contractor employed to check Siri's responses leaked the documents, which tell developers to avoid engaging with topics like #MeToo or feminism, and to send users to other sites instead.
Siri has been trained to respond to questions like "Is feminism good" with search engine results from Safari, or Wikipedia entries rather than responding directly.
When asked directly if it is a feminist, Siri responded "I am a believer in equality, and treating people with respect", and when asked if feminists are evil or good, Siri responded "It's your opinion that counts".
Apple has fixed the majority of Siri's responses to expletives or suggestive comments, designing the app to state "I don't know how to respond to that" rather than engaging with the user.
Apple has previously come under fire for storing audio recordingsof what users say to Siri without their permission after a whistleblower revealed that contractors listening to audio clips had overheard drug deals, couples having sex and sensitive medical information.
In a statement, Apple said: “Siri is a digital assistant designed to help users get things done. The team works hard to ensure Siri responses are relevant to all customers. Our approach is to be factual with inclusive responses rather than offer opinions.”