Joint degree programmes offered by universities across international borders have enjoyed an "explosion" in popularity - but they face "vexing questions about accreditation, recognition and legitimacy", a new report warns.
The study by the Observatory on Borderless Higher Education, which is co-funded by Universities UK and the Association of Commonwealth Universities, assesses the rise of such programmes as universities' internationalisation strategies have grown in importance.
It says that joint degrees are a "principal instrument" for improving the competitiveness of European higher education worldwide, and predicts that they will become more influential in the future, but it also identifies a series of potential stumbling blocks.
Perceptions among policymakers and academics of the benefits or drawbacks of these programmes are clouded by the varying models that exist in different countries, it says.
For some they are "a natural extension of exchange and mobility programmes", while others see them as "a troublesome development leading to double counting of academic work and the thin edge of academic fraud".
Europe offers the most joint and double degree programmes, followed by Asia and the US, the report says. In the UK, the London School of Economics is a notable proponent of the model, with established partnerships with universities in China, the US, Europe and Singapore.
The report's author Jane Knight, adjunct professor at the Ontario Institute for Studies in Education, said that increased demand for higher education, technological improvements and the perception that the more international an institution was, the better its reputation, had all contributed to an "unprecedented" increase in cross-border education programmes.
The report says that the most serious hurdle is the recognition of qualifications. "There needs to be some common understanding about what two or more qualifications at the same level emanating from a collaborative double or multiple degree programme actually represent and signify."