Since it's inception, Twitter has evolved tremendously, and is now a platform for just about everybody to vent on. However, with its growing popularity also came growing exposure, meaning, you cannot just say whatever you want anymore. Anything on your Twitter may be used against you in a court of law.
Key witness in the Trayvon Martin murder case Rachel Jeantel figured this out recently, as she was recently forced to delete over 50 incriminating tweets from her personal Twitter account. The tweets primarily contained references to alcoholic consumption and drug use, neither of which has anything to do with the case. Nonetheless, the defense could potentially use those tweets against her to prove her unreliability.
One of her tweets read, "Omg people calling n praying n sh*t lol I need a drink smoke and a pray my head killing me right now cannot wait when this day end."
Though the tweets could possibly be used, the defense team did previously fail in attempting to make Trayvon Martin's marijuana use admissible in court.