"Mob rule" is defined as "control of a political situation by those outside the conventional or lawful realm, typically involving violence and intimidation." The technically correct term is "Ochlocracy."
"Mob rule" is often cited as an objection to democracy. However, democracy is actually the opposite of "mob rule." Democracy is based upon the rule of law. This means that decisions must conform to principles listed in a constitution, which specifies valid procedures within the organization or state. Any decision taken must follow "due process of law." This ensures that the principles in the constitution are observed. "Due process of law" might prescribe a hearing, where all sides of an issue can be presented. Next, there might be a period during which arguments can be evaluated. Finally, a vote might be taken to reach a decision. However, objections can be raised, if someone feels that the decision violates fundamental rights embodied in the constitution. This would typically lead to a judicial proceeding where all evidence is presented and weighted by specialists, before a conclusion is reached. So, the normal process of decision making in a democracy involves presenting information, participating in decision making, and then getting feedback as to the result of the process. If a failure of due process or some other violation of constitutional principles is thought to have occurred, a judicial proceeding is required before the decision is finally accepted.