From: Rabbi Moshe Sofer
To: Rabbi Yechezkel Segal
The Chasam Sofer addresses why the Rambam disqualifies matzah made from untithed produce (tevel) for the Pesach obligation. He offers multiple justifications, including mitzvah haba'ah b'aveirah.
Source: Shu"t Chasam Sofer OC §137