Each republican magistrate held certain constitutional powers. Only the People of Rome (both plebeians and patricians) had the right to confer these powers on any individual magistrate. The most powerful constitutional power was imperium. Imperium was held by both consuls and praetors. Imperium gave a magistrate the authority to command a military force. All magistrates also had the power of coercion. This was used by magistrates to maintain public order. While in Rome, all citizens had a judgement against coercion. This protection was called provocatio (see below). Magistrates also had both the power and the duty to look for omens. This power would often be used to obstruct political opponents.