Freedom of expression was the right to express one's opinions in whichever manner one chose, within reason.
In 2372, Odo was ordered by Captain Benjamin Sisko not to interfere with the strike that employees of Quark's were staging, as to do so might deprive them of their freedom of expression. The caveats were that their protest would have to remain peaceful and that they would have to allow patrons to enter through the second level entrance. (DS9: "Bar Association")