Julia has a longstanding research interest in work and economic life that started from a concern with the variability of capitalist employment relations which she explored in her 1993 book, Privatization and Employment Relations: The Case of the Water Industry (Cassell) and a number of journal articles and book chapters on the restructuring of work and employment in privatised utilities and the use of franchising in milk distribution. In the mid 1990s, she started to research prostitution as a form of non-standard work and to address questions about what, precisely, is exchanged in the prostitution contract and the diversity of prostitution in terms of its social organisation and the power relations it involves (both globally and nationally). She has also undertaken research on sex tourism, on child prostitution (Prostitution, Power and Freedom, 1998, Polity; Children in the Global Sex Trade, 2005, Polity), and on child migration. In 2001, she was PI on an ESRC funded project examining the markets for migrant sex and domestic workers in the UK and Spain. This research has informed a number of publications that explore that definitional problems associated with the term 'trafficking', critique dominant discourse on 'trafficking as modern slavery' and challenge the framing of 'trafficking' as a problem of transnational crime as opposed to a migrants' rights issue. 

At a theoretical level, Julia has been concerned to link her research on prostitution, sex tourism, 'trafficking' and 'modern slavery' to critiques of dominant liberal fictions about contract, freedom, citizenship, human rights, and childhood, as well as to questions of power, especially the question of how we can critique those theoretical traditions that approach power as domination without slipping into the relativism and subjectivism of much post-modern and post-structuralist theory. These themes were further developed in her book, 'Modern Slavery: The Margins of Freedom', Palgrave Macmillan, 2015, and the Leverhulme Major Research Fellowship she held from 2013-16.

Julia currently holds an ERC Advanced Grant for a project titled 'Modern Marronage? The Pursuit and Practice of Freedom in the Contemporary World'. The project asks whether histories of marronage and enslaved people’s flight and fugitivity, as well as other strategies employed by enslaved people in an effort to move closer to freedom, and whether histories of slave states’ efforts to prevent flight and marronage and otherwise restrict the freedoms of the enslaved, can shed light on the experiences of marginalised and rightless people today.