In “Sex selection and regulated hatred”1 John Harris launches a vehement critique of the Human Fertilisation and Embryology Authority’s recent report Sex Selection: options for regulation, raising several issues that merit discussion.He begins by complaining about the recommendation that because of the theoretical risk associated with the use of flow cytometry as a method of sperm sorting, its use should be restricted for the moment to cases in which a clear medical benefit is to be gained from its use. Harris (...) objects that in this recommendation “an absurdly high standard of caution is employed”, since a theoretical risk is associated with almost all medical procedures. This objection is misplaced: as paragraph 142 of the report indicates, the phrase “theoretical risk” is to be understood here in the light of the earlier discussion of the risks arising from the fact that flow cytometry exposes sperm to laser energy, a procedure which is known to be liable to damage DNA. Since the application of flow cytometry to humans is a new procedure, the risk of human genetic defects caused this way is still only “theoretical”; nonetheless it is serious enough to warrant caution—hence the recommendation that at present flow cytometry should be available only when its use brings clear medical benefits. The HFEA has recently been criticised by some for not being cautious enough when permitting the use of intracytoplasmic sperm injection even though in that case there are clear medical benefits from its use. It is extraordinary that Harris should now criticise the HFEA for not throwing caution to the winds concerning flow cytometry.Harris’ next point concerns the justification for this suggestion that preimplantation sex selection should be available only where it is undertaken for medical reasons. The obvious way to justify this would appear …. (shrink)