Lobbying consists in the effort to influence the decision of government policy makers. In a liberal society, the use of coercion to obtain one’s ends needs ethical justification. Thus, to the extent that one is lobbying the government to exercise coercion on one’s behalf, such lobbying needs ethical justification. This essay argues that the desire to obtain a benefit for oneself at the expense of others that one cannot obtain through voluntary exchange can never serve as such a justification. It further argues that the action of engaging in such ethically unjustified lobbying is morally equivalent to an attack on those who will suffer a loss if it is successful. The essay then applies the legal doctrines of self-defense and defense of others to identify an ethically justified form of defensive lobbying, and traces several of its implications.