Electrosurgical instruments including a jaw angle detection system

An electrosurgical instrument includes an elongated shaft, an end effector, a drive shaft, and a switch assembly. The end effector is coupled to a distal end portion of the elongated shaft and includes opposing first and second jaw members. The end effector is configured to move between an open configuration and a closed configuration. The drive shaft is operably coupled to the end effector to move the end effector between the open and closed configurations. The switch assembly includes a first electrical contact and a second electrical contact. The first electrical contact is coupled to the drive shaft and configured to move with the drive shaft. The first electrical contact is configured to engage the second electrical contact in response to a movement of the drive shaft to determine a first angle between the first and second jaw members.