Some search terms to try when searching databases for this topic:
Censorship
Freedom of Speech
Free speech
First amendment
Hate speech
Misinformation
Political Rights
Censorship: the suppression or prohibition of any parts of books, films, news, etc. that are considered obscene, politically unacceptable, or a threat to security.
First amendment: an amendment to the US Constitution that prohibits any law limiting freedom with respect to religion, expression, peaceful assembly, or the right of citizens to petition the government.
Freedom of speech: The right to express oneself, either orally or in writing, without fear of governmental restraint or retribution. In the U.S., this freedom is protected by the 1st Amendment to the Constitution, and is considered essential to the vitality of representative government.
Hate speech: speech that impugns an individual or group based on race, ethnicity, religion, gender, or sexual orientation.