Human rights activists have urged consumers to be conscious of the labor practices employed by manufacturers, especially in developing nations, saying that if we accept moral responsibility for our impact on third world workers, we must buy products from manufacturers that do not take advantage of their workers  It is nearly impossible, however, to determine which manufacturers are employing fair labor practices
Because of this impossibility there can be no moral obligation to choose products in the way these activists urge, because
A person cannot have a moral duty to do what is impossible.