Media Briefings

Same-Sex Partnership Laws Reduce Syphilis Rates

  • Published Date: July 2008

The prevalence of the sexually transmitted infection syphilis has fallen by nearly a
half in parts of continental Europe as a result of recently introduced national laws
that allow for the legal recognition of same-sex partnerships.
That is the central finding of new research by Professor Thomas Dee, published in
the July 2008 issue of The Economic Journal.
How might these laws have influenced the prevalence of sexually transmitted
diseases such as syphilis? Professor Dee conjectures that:
‘The legal recognition of same-sex partnerships may reduce the levels of
sexual promiscuity among homosexuals by creating legal and financial
incentives as well as social norms similar to those associated with
heterosexual relationships.’
What’s more, by reducing the social stigma of homosexuality, these laws could limit
the transmission of sexually transmitted infections by discouraging furtive, high-risk
sexual activity and the ‘closeting’ of sexually active homosexuals in
heterosexual relationships.
The study uses World Health Organization (WHO) data on European countries from
1980 to 2003. During this period, nine European nations – Denmark, Norway,
Sweden, Iceland, Netherlands, France, Germany, Finland, and Belgium – introduced
new laws that allowed same-sex couples to form legally recognised partnerships
and, in some countries, marriages.
The wave of new laws legalising same-sex partnerships across Europe created legal
rights (such as treatment as a couple for the purposes of inheritance tax), economic
benefits (including joint tax assessment) and a nationwide social recognition similar
to that available to married heterosexual couples. Most of these laws followed the
design of Denmark’s landmark ‘registered partnership’ law introduced in 1989.
This study identifies the effect of same-sex partnership laws on syphilis rates by
comparing the changes in countries following the introduction of these laws to the
contemporaneous changes in neighbouring countries that did not adopt the laws.
Analysis of the WHO data indicates that same-sex partnership laws reduced syphilis
rates by approximately 43%.
Syphilis is a particularly appropriate sexually transmitted infection for this analysis
because it appears to be relatively common among homosexual men (unlike
gonorrhoea) and because the detection of syphilis typically occurs soon after
infection (unlike with HIV, the human immunodeficiency virus).
How might these results contribute to the debate over the legal status of same-sex
relationships? Professor Dee comments:
‘Any policy that can reduce syphilis rates is beneficial from a public health
perspective, particularly because of the role that syphilis is thought to play in
the transmission of HIV.’
‘But for many observers, the broader social significance of this finding may be
in what it suggests about how the legal recognition of same-sex partnerships
influences the patterns of commitment in same-sex relationships and, possibly
by extension, the overall social standing of marriage.’
Notes for editors: ‘Forsaking All Others? The Effects of Same-Sex Partnership
Laws on Risky Sex’ by Thomas Dee is published in the July 2008 issue of The
Economic Journal
Thomas Dee is an associate professor of economics and director of the Public Policy
Program at Swarthmore College.
For further information: contact Thomas Dee on +1 610 690 5767 (email:; or Romesh Vaitilingam on 07768 661095 (email: