Adultery was "officially" illegal (but of course, still often practiced) in Turkey until 1996. It was taken off the books as a crime because women were being punished for it at a far greater proportion than men.
Periodically, since then, conservative governments have tried to get adultery once again declared a crime. This has failed, mostly due to arguments that doing so would jeopardize Turkey's ongoing attempts to join the EU.
As background:
-- Turkey has been a secular and democratic nation-state since the 1920s.
-- Stoning anyone for any reason is illegal. "Honor killings" have been known to take place from time to time in rural areas (I stress, these are ILLEGAL).
-- 77% of Turks in a 2011 survey said they were
against stoning adulterers:
LINK
If you want to learn more about what modern Turkey is like, I heartily recommend the amazing novels of Nobel Prize winner
Orhan Pamuk or the beautiful films of
Nuri Bilge Ceylan. I'm sure ThinkHard, lavy, and Yashim have more recommendations.