Tech that can decode your brain activity and reveal what you're thinking and feeling is on the horizon, says legal scholar and ethicist Nita Farahany. What will it mean for our already violated sense of privacy? In a cautionary talk, Farahany warns of a society where people are arrested for merely thinking about committing a crime (like in "Minority Report") and private interests sell our brain data -- and makes the case for a right to cognitive liberty that protects our freedom of thought and self-determination.