Justice Minister Hideo Usui has granted special residence permits to an Iranian family of four who have overstayed their visas, lawyers representing the family said.

But while permission was granted to this family, based in Japan for about 10 years, the minister rejected petitions filed in December by four other families with a combined 13 members, the lawyers said Friday.

The ministry detained the fathers of the four families to begin the expulsion process but temporarily allowed the mothers and children to remain at home. The four families are planning to file suit against the decision.

There are no set guidelines under which special permission is granted, and decisions are left to the discretion of the justice minister.

The five families make up the second group of foreigners to jointly file a petition to stay in Japan after overstaying their visas.

The family that was allowed to stay includes a teenage boy who is a second-year junior high student.

Usui earlier this year gave special residence permits to 16 members of four families with children either in high school or about to enter junior high. They were part of the first group of foreigners — 21 people from five families — to file a joint petition in September last year.

It appears Usui at least partly bases his decisions on whether a family has children who are approaching or are in their early teens, have spent many years at school in Japan and are accustomed to Japanese society.

A senior Justice Ministry official said, “We took into consideration cases in which the children would have trouble studying or living in their home countries.”

According to the Asian People Friendship Society, which supports people who have overstayed their visa, the family given permission to stay Friday comprises a father who came to Japan around 1990, a wife and son who followed suit a year later, and a daughter born in Japan.

Two of the rejected families have daughters in sixth grade, while the two others have preschool children born in Japan, the APFS said.

APFS representative Katsuo Yoshinari complained that families with children in sixth grade should have been approved. “I also think it cruel that they are taking the strategy of starving the families out by detaining the fathers,” he said.