Walking Before Someone Who is Praying Shemoneh Esrei

Two reasons why walking before one who is davening Shemoneh Esrei is prohibited. What is the nafka mina? Under what circumstances would it be permissible?

Rabbi Zakutinsky recently published a halacha sefer in English (with helpful Hebrew footnotes) addressing the laws and customs of the Jewish wedding, from the engagement period through shana rishona. Written for laymen and rabbis alike, The Gates of Joy elucidates and explains the halachos and customs of Ashkenazim, Sephardim, and Chassidim, including Chabad Chassidim. See a sample of The Gates of Joy here and email avizakutinsky@gmail.com to order. Say you saw it on OU Torah for a 25% discount!