The chair of governors at Cardiff Metropolitan University has warned that legal action could be taken if the college is forced to merge.
Barbara Wilding says she has seen no evidence that plans to merge with the University of Glamorgan and University of Wales, Newport, are necessary.
The proposals followed a Higher Education Funding Council review.
Education Minister Leighton Andrews says it will create the most powerful higher education bodies in the UK.
But Ms Wilding is concerned that without a detailed business plan, the college governors cannot make an informed decision on whether or not to support a "super" university plan.
"There has to be a reason for doing it and that reason has to be underpinned by evidence, a financial basis or whatever else, it has to be underpinned by evidence," said the former chief constable of South Wales Police.
"We have asked and asked, in order that we can be engaged in this debate, for that evidence the minister believes that he has - and we've had nothing".
Mr Andrews is seeking a voluntary merger, but he does have the power to force it through.
Ms Wilding says they are prepared to fight such a move in the High Court.
"What we would have to do is go to judicial review, to stop those powers being used, in order that it can be reviewed against the evidence," she stated.
"Unless we get the evidence beforehand, we can't engage in the debate."
"Our responsibility is to the staff and the students and unless we can see benefits of reconfiguration in a different way, then why should we go through this process?"
"At the moment, we're operating in a vacuum."
But the Welsh government minister believes that the evidence for a merger is clear.
"The market for universities is getting tougher. It's a much more competitive market that they'll be facing across the border in England and that will have an impact on Welsh institutions as well," said Mr Andrews.
"But I think there is a much more positive case, which is that we can create in the south east of Wales, one of the most powerful higher education institutions in the whole of the UK.
"It will be the second largest metropolitan university in the UK after Manchester Metropolitan University and it will be able to provide a wide range of student experiences and will contribute to the economy of south east Wales. "
A spokesperson for the University of Glamorgan said it had always recognised the logic of a single merged university because it would be of a size and scale to compete with its major competitors over the border.
It supports the merger, providing it does not endanger Glamorgan's own academic and financial position.
The University of Wales, Newport, favours the creation of a new university, rather than a merger of existing parts, as long as it continues to encourage wider participation and industry links in Gwent area.