A group of legal and political scholars has protested the government's abrupt change of its legal interpretation to allow a senior prosecutor to put off his retirement.
The government decided at a cabinet meeting in late January to delay until August the retirement of Hiromu Kurokawa as the head of the Tokyo High Public Prosecutors Office.
Kurokawa was to have retired in early February when he turned 63, under the law governing prosecutors.
However, the government cited a provision in the national public servants' law dating back to 1985 that allows retirement dates to be pushed back.
Criticism rose when it came to light that the Justice Ministry's legal view had been, since 1985, that the provision did not apply to prosecutors.
Pressed to account for the inconsistency, Prime Minister Shinzo Abe told the Diet last week that prosecutors are national public servants and that his administration now considers the provision regarding the extension of the retirement age does apply to them.
Justice Minister Masako Mori affirmed Abe's remarks in the Diet on Thursday. She said her ministry had changed its legal interpretation a week before the cabinet decided to extend Kurokawa's tenure.
A group of constitutional and political scholars told reporters on Friday that if the serving administration can freely change the way laws are interpreted, the rule of law will be shaken to its foundation.
They said personnel rules for prosecutors -- who at times investigate crimes committed by those in power -- should not be decided single-handedly by the cabinet without debate and decision-making in the Diet.
Some observers say the Abe administration decided to delay Kurokawa's retirement so he can be named the next prosecutor-general -- the nation's top prosecutor.
Abe has denied that his government handled personnel affairs arbitrarily. He said it has always appointed the right people to the right posts.
But calls for a more detailed explanation are rising, even from prosecutors. At a meeting of senior prosecutors this week, a chief prosecutor from a district office reportedly said the government's decision may undermine public trust in prosecutors, despite their efforts to keep political neutrality.