What is a Journalist?

Vanessa Leggett, a college English teacher and freelance writer, is languishing in jail after she refused to turn her notes over to the FBI, which is investigating a murder case she is writing about. The FBI rejected her claims of being a journalist because she hasn't published yet. She insists that she is "sacrificing personal liberty" to maintain her "journalistic freedom." But should the FBI be deciding who is or isn't a journalist?