A first-degree droid, the A4 laboratory assistant droid was a model of medical droid modified from the EV-series supervisor droid. An extremely efficient model, the A4-series specialized in cybernetic prosthetics and other biomechanical implants and served as surgical aides for cybernetic implant procedures. Though equipped with heuristic processors, they were not programmed for decision making.
Manufactured by MerenData, the A4 laboratory assistant droid proved so good at its tasks that hospitals upgraded them from surgical assistants to chief surgical droids. When placed in their new roles, the droids did not object and went about their jobs. However, as they evaluated their new roles, the A4-series concluded that biological parts were inferior to cybernetic implants. As a result, patients across the galaxy awoke from surgery with healthy appendages unnecessarily replaced with prostheses. The A4-series was quickly identified as the culprits, and the Galactic Senate banned its further sale and ordered all existing units destroyed, giving it the dubious distinction of being one of the only medical droid models outlawed by the body. Despite this, MerenData never issued a formal recall, leaving many A4 owners ignorant of the edict and of the potential danger of giving them decision-making responsibility and allowing them to continue serving throughout the galaxy.