A group of South Korean law school students said Friday that they have lodged a constitutional petition against a quota that limits the number of candidates allowed to pass the bar exam.

In the petition filed with the Constitutional Court, third-year students at six graduate-level law schools nationwide claimed the quota violates their fundamental human rights, including freedom of occupation.

"Anyone who successfully completes law school should be able to pass the exam without much difficulty," the students said.

"Admission into law school is already controlled by what the society believes is the appropriate number of lawyers in the country. The quota on the exam passage, therefore, is an unnecessary restriction to our occupational freedom."

The petition comes after the justice ministry announced in April that it will keep the exam passage rate at about 75 percent next year, when the third test under a new qualification system will be administered.

Under the new system introduced in 2009, law school graduates from 2012 onwards are required to take the new bar exam in addition to completing three years of a graduate level law school program.

Traditionally, prospective lawyers were only required to pass the old bar exam and complete two years of training at the Judicial Research and Training Institute run by the Supreme Court. The old system will be phased out in 2017.

Last year, 87 percent of test-takers passed the new bar exam, with only 75 percent passing it this year. (Yonhap News)