Nine new judges will be appointed to the ECJ — which consists of three different courts — marking the first stage of the reforms.
The changes will see a number judges' posts transferred from the Civil Service Tribunal to the ECJ General Court.
While the reforms were designed to address the backlog in cases at the Luxembourg-based court, the plans have been met with widespread criticism from some legal experts.
A recently released report written by EU General Court judge Franklin Dehousse said the expansion was "manifestly excessive," and "a great example of a purely mechanical vision of public service reform."
Dehousse argued the reforms would not address the backlog in cases, as designed, and said any benefits were "strongly overestimated."
#CJEU reform: Excellent paper by GC judge Franklin Dehousse which offers a devastating critique of EU Reg 2015/2422: https://t.co/0zFGErpUvL
— Laurent Pech (@ProfPech) March 28, 2016
The plans for ECJ reform triggered criticism of excessive EU spending after it was revealed the changes would cost US$26 million (€22.9m) a year, amounting to 6.6 percent of the court's overall budget.
"This is hardly an efficient — or an economical — strategy," Dehousse said.
The changes, which will see a judge from all 28 member states represented in the ECJ, have also raised concerns that many countries could act out of self-interest, which could ultimately weaken the court's independence.
"Equality of the member states in the appointment of judges has become the keystone of the system, the independent appointment process for the nomination of judges having been abolished," Dehousse said.
