If a Jewish friend owns a restaurant, or makes certain foods they sell for a living however they do not have a hechsher from the beis din of the place then, 1) can one eat there even if it does not have a hechsher provided you trust the owner that all food is kosher. 2) if it is open on shabbos can one still eat there in the week. What are the sources for it being mutar or assur to eat there?
Answer:
One must not eat in a restaurant that is open on Shabbos, and therefore cannot receive a kashrus certificate.
If the restaurant is open on Shabbos, there are obviously plenty of workers who are not particular about halachah, and they cannot be trusted for matters of kashrus without appropriate supervision.
This is in addition to the problem of food that is prepared on Shabbos.
Best wishes.
