As the membership status of this group of former colonial subjects came into question, what form did labor protectionism take when its central basis of action was removed? With membership status unclear, where would Koreans be placed in the pecking order of job entitlement? As we will see, labor protectionism would morph into its 4th form: discrimination.
The legal status of Koreans in Japan has swung both ends of the pendulum, so to speak, twice over. Koreans were full foreigners as the Japan-Korea Treaty of Amity was consummated in 1876, as excluded from certain jobs by Ordinance 352 and through their protectorate period by 1905. As an annexed state from 1910 to 1945, Koreans became Japanese though not "true" Japanese but "colonial" Japanese (Iwasawa 1986 cited in Kearney 1998: 201) or those from Gaichi -- external territories -- who had family registers or Koseki that were separate from those of the Naichi Japanese - or those in Japan proper (Morris-Suzuki 2010: 43) - and whose citizenship rights were realized only to the extent that they helped in serving out their economic function as a colony (Weiner 1994: 47). Koreans in Japan then reverted back to foreigner status by 1952 when the San Francisco Peace Treaty took effect but, through a special regulation, were allowed to stay indefinitely even without clear residence status (Morris-Suzuki 2010: 114).
By 1965 when the Treaty of Basic Relations between South Korea was signed, Koreans in Japan up to the second generation who chose South Korean nationality were granted permanent resident status. By 1981, all Koreans were granted special resident status. In summary, in terms of the pecking order of job entitlement, Koreans were foreigners until 1910, "almost" Japanese nationals until 1952, back to foreigners up to 1965 and finally settling in as special permanent resident by 1965/1981 onwards.
Labor protectionism as discrimination was seen primarily in the exclusion of foreigners from certain local jobs. Morris-Suzuki (2010: 177) reports that throughout the 1950s and 1960s public sector jobs were reserved only for Japanese nationals. This exclusion, Kearney (1998: 215) explains, isn't even based on actual restrictions explicitly stated in law but rather on the customary weight and deference given to "administrative guidance," or subsequent implementing rules and regulations issued by the bureaucracy. As this "administrative" authority constituted itself into the formal bases of job exclusion for foreigners in the public sector, it was inevitable that discriminatory practices would spill over not just into non-public sector jobs but also into non-job related aspects of the lives of foreigners. Morris-Suzuki (2010: 177) further cites that even private companies would not hire Koreans as permanent employees. Concurring with this, Hwaji (2010: 335-336) adds that Koreans were also excluded from bank loans, scholarships, government health and other social benefits.
That post-WWII labor protectionism, manifesting itself in the form of discrimination, was probably most felt by the Koreans was due in no small way to the fact that Koreans were the single, most pervasive foreigner presence in Japan for half a century after the end of WWII -- making up above 90% of foreigners up to 1959, above 80% up to 1985, dipping to below 50% only in 1995.