Wittingly or unwittingly, individuals do things that injure other individuals. For society to function, it must provide individuals with incentives not to do so, through rewards and punishments, regulations and fines. By polluting the air, one harms anyone who breathes. The legal system has an important role here. If I injure you, you should be able to sue me.
Of course, individuals have a moral responsibility not to injure others. Indeed, this is perhaps the central moral imperative--do unto others as you would have them do unto you, and do not do unto others as you would not have them do unto you.
Immanuel Kant, with his categorical imperative, provided the philosophical foundations for those who wanted an alternative basis for ethics than that provided by religious aphorisms. But modern society cannot and does not simply rely on individuals doing the "right" thing. It provides carrots and sticks.
Motivating corporations to do the right thing is even more difficult. After all, corporations don't have a conscience; it is only the conscience of those who run the corporation, and as America's recent corporate scandals have made all too clear, conscience often takes a backseat to profits.