Nevertheless, the Fujiwara were not demoted by Daigo but actually became stronger during his reign. Central control of Japan had continued to decline, and the Fujiwara, along with other great families and religious foundations, acquired ever larger shōen and greater wealth during the early tenth century. By the early Heian period, the shōen had obtained legal status, and the large religious establishments sought clear titles in perpetuity, waiver of taxes, and immunity from government inspection of the shōen they held. Those people who worked the land found it advantageous to transfer title to shōen holders in return for a share of the harvest. People and lands were increasingly beyond central control and taxation, a de facto return to conditions before the Taika Reform.
when did religious establishments obtain legal status? (If the question is unanswerable, say "unanswerable")
unanswerable