Public reaction to the assassination of President Garfield forced Congress to pass the Civil Service Reform Act. The law established a three-person, bi-partisan panel to develop exams to hire federal employees based on merit. The act initially covered 10% of federal employees, but became the basis for most of the Civil Service of today.
Reformers had long been calling for an end to the "spoils system" in civil service appointments. However, the assassination of President Garfield provided the needed push to make the change. The spoils system was the system where the President appointed people who supported then in one way or another to government jobs. Before the reform almost every government job was appointed by the President.
President Arthur, who himself had been a product of the spoils system, surprised his critics by becoming a vocal supporter of the reform. A bi-partisan, three-person commission was created to oversee the newly-established Civil Service System. Arthur appointed three individuals long identified with civil service reform to serve as its commissioners.
The new law called for open competitive exams for all jobs classified as civil service jobs.