Inspired by this comment, there are Chazaka's (presumptions) and principles of נאמנות (trustworthiness) in Halacha that no longer hold in our practical experience. One example is עד אחד נאמנן ...
There are a number of organizations that offer Vegan Certification for food products; the concept is the same as kosher certification, (though that is the only similarity). Examples would be Vegan.org ...
May one eat a meal in the home of one who attended yeshiva and who one considers trustworthy vis-a-vis making sure everything is kosher for their guests, however, one is reasonably certain they do not ...
Say I visit a bakery, restaurant, jail, hospital, or nursing home. And say I already know that the food there is kosher. Must I still check the kashrut certificate every time I visit? (Gershon ...
In a bulk food store, must I ask to see the original label every time I return and buy my favorite food?
I know that where I live, some foods don't need kosher certification. But most do. Say I go to a reliable bulk food store, ask to see the original bucket that a certain food came in, see a reliable ...