In May 2008 in the abortion amendments to the Human Fertilisation and Embryology Bill (now Act), David Hamilton voted for the abortion time limit to be lowered to 22 weeks against scientific and medical consensus which is currently 24 weeks. After four separate parliamentary votes on varying time limits, the majority of MPs voted to keep the abortion time limit at 24 weeks, in keeping with scientific and medical consensus, hence no abortion amendments were added to the bill.
In February 2015 David Hamilton voted in favour of allowing mitochondrial donation, which would allow women who carried mitochondrial diseases to give birth to children who would not inherit the disease. An October 2014 briefing report by the Human Fertilisation and Embryology Authority (HFEA), which had been investigating the issue for three years, stated that there was no evidence to show that mitochondrial donation was unsafe. However, some religious groups had said that such procedures should not be allowed. After clearing both Houses mitochondrial donation is now legal, regulated by the HFEA.
David Hamilton was one of 79 MPs who signed Early Day Motion 377 noting the achievements of Charles Darwin, and calling for Darwin's birthday to be designated a public holiday to honour "one of the fathers of modern science and one of Britain's greatest, if not the greatest, scientific minds."
Libel Law Reform
In February 2010, David Hamilton signed Early Day Motion 423 calling for a reform of the English libel law. The motion noted that human rights activists, scientists, writers and journalists are currently prevented from publishing, and the public prevented from reading, matters of strong public interest due to the chilling effect of the law.
In February 2010, David Hamilton signed Early Day Motion 524: Recognising Climate Change which states that "this House agrees that climate change is happening and is man-made" and calls this statement a "fact, which has the support of the overwhelming majority of the scientific community".