From: Rabbi Moshe Sofer
To: Rabbi Ber
A Jewish merchant's non-Jewish agents purchased wheat by ship during Pesach, raising concerns about Shabbos violation and whether the wheat constitutes chametz she'avar alav haPesach. The Chasam Sofer rules leniently, reasoning that the leavened grains constitute a mekach ta'us (mistaken transaction).
Source: Shu"t Chasam Sofer OC §134