Is it illegal to write a negative song about person using their full name?

It depends on the jurisdiction and the specific circumstances. In general, it is not illegal to write a negative song about a person using their full name, as long as the song does not contain defamatory or libelous statements. However, there are some exceptions to this rule. For example, in some jurisdictions, it may be illegal to write a song that incites violence or hatred against a particular person or group of people. Additionally, some jurisdictions have laws that protect the privacy of individuals, which could potentially be violated by writing a negative song about someone using their full name.