What is the ruling on consuming foods in America that are feared to contain pork derivatives in their hidden ingredients, such as oils or sauces, and how can one verify this?

The summary of the fatwa is that it is originally permissible to eat meat in American restaurants, because their origin is Christianity, and the slaughtered animal of a Christian is permissible. However, it is more scrupulous to refrain from eating there, or to prepare the food oneself, or to eat in Muslim restaurants. If it is known that the meat or fat is from pork, then it is not permissible to consume it. The general rule for foods (other than slaughtered animals) is permissibility until the contrary is proven. As for the ruling on using a cooking utensil that contained pork, it is explained in another fatwa.