free speech vs incarceration

free speech

noun
  • The right to express an opinion in public without being restrained or censored. 

  • Expressions that are or should be allowed in some moral or legal context. 

incarceration

noun
  • The act of confining, or the state of being confined; imprisonment. 

  • A constriction of the hernial sac, rendering it irreducible, but not great enough to cause strangulation. 

How often have the words free speech and incarceration occurred in a corpus of books? (source: Google Ngram Viewer )