When asked by journalist Tom Whipple what evidence the MP had used in deciding to support the motion, Cohen responded, "There is a lot of evidence, and traditionally it has had very successful outcomes. Myself and my wife have benefited. Prince Charles has made a very strong case for it too. The implication of your comment could also be ascribed to any number of mainstream medicines – tests on animals are not necessarily appropriate for humans, for example." 
Tom Whipple requested further clarification of Cohen's position on mainstream medicine testing, and asked for evidence of positive trials for homeopathy. Cohen responded, "It’s not my EDM. I’m happy with the evidence I have encountered. I suggest you contact the main sponsors of the EDM." Cohen also forwarded an email from the British Homeopathic Association.
Following the publication of the House of Commons' Science and Technology Committee's report "Evidence Check 2: Homeopathy" in February 2010, Harry Cohen signed Early Day Motion 908: Science and Technology Committee Report on Homeopathy, which was critical of the report.
Harry Cohen has signed a number of Early Day Motions that support the use of herbal medicines. These include EDM 1103: Traditional Herbal Medicinal Products Directive (2005), EDM 1549: Herbal Clinic at The Royal London Homeopathic Hospital (2008), and EDM 2080: Herbal Remedies (2008).
Harry Cohen signed the February 2009 Early Day Motion 754: MMR Vaccine and the Media supporting the use of the MMR vaccine. The motion expressed disappointment with the reporting of the vaccine by Jeni Barnett on her LBC radio show in January 2009, and expressed the hope that future reporting of the issue of MMR would be less sensationalist and more evidence-based.
In May 2008 in the abortion amendments to the Human Fertilisation and Embryology Bill (now Act), Harry Cohen voted to keep the current time limit of 24 weeks in line with the scientific and medical consensus.
In 2006, MPs were asked three questions by the Rough Guide's Mark Ellingham on how seriously they took climate change as politicians and as responsible, active citizens. Harry Cohen replied:
- "1: Very important as it can cause massive economic disruption, humanitarian crises and war.
- 2: It can introduce relevant taxes and stricter regulation to limit carbon emissions. It can be in the forefront of greener technology and work for a far better international response.
- 3: Better energy efficiency, including improved loft insulation, switching appliances off instead of leaving on standby, only boiling a kettle with the amount of water needed, and energy saving lighting. I am considering a more efficient boiler and solar panels for the future."
In January 2010, Harry Cohen 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".
Libel Law Reform
In December 2009, Harry Cohen 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.
The motion was tabled following the recent formation of Libel Reform Coalition, which has the backing of Index on Censorship, English PEN and Sense about Science. Sense about Science have been campaigning in defense of a member of its board of trustees, author and journalist Simon Singh, who has been sued for libel by the British Chiropractic Association. They issued a statement entitled "The law has no place in scientific disputes".