The spare embryo--a red herring in the embryo experimentation debate.

Whenever embryo experimentation is discussed, the question of whether it is preferable to use spare or specifically produced ('research') embryos for destructive embryo experimentation always enters the debate at some stage. This question is analysed, and it is suggested that the distinction is morally uninteresting, but rhetorically useful for both sides in the debate. It is further suggested that part of the force of this distinction is caused by the fact that it is parasitic on a real moral distinction based on the degree to which the gametes used in the experiment are obtained by explicit or implicit coercion.