Date: 24 Tammuz
From: Rabbi Moshe Sofer
To: Rabbi Aharon Fulda
The Chasam Sofer rules against the Pri Megadim, holding that for an ordinary person the obligation of kriah lapses once the proper moment passes without tearing. Therefore, someone who could not perform kriah on Shabbos due to the prohibition has no obligation to tear on Motzaei Shabbos, as the principle of 'mah d'havah havah' applies.
Source: Shu"t Chasam Sofer YD §323