Are there special cases in which meat not slaughtered in Islamic way is allowed to eat?

It is well known that Muslims are forbidden to eat meat which is not slaughtered in Islamic way. But, what is the rule for eating meat sold in public markets or public places in **non-Muslim countries**. For example, eating lunch at work place, school cafeteria or eating dinner in a friend's home, ... etc? Is there any exclusion or special permission for these cases to eat meat which is not slaughtered according to Islamic way?