EU treaties are "consistent with automatic succession of both the seceding state and the rump state" but international leaders "have a vested interest in centralisation" and "are biased against secession", said Professor Dr Roland Vaubel, an adviser to Germany's economics ministry.
A string of European leaders, including EU Commissioner Jose Manuel Barroso, Vice-Commissioner Viviane Reding and EU Council president Herman van Rompuy, have all suggested Scotland would need to reapply as a new state if it left the UK.
Dr Vaubel said their position is based on a desire "to renegotiate the terms of Scottish membership", to bring them into the euro and Schengen borderless-travel area and give up the budget rebate negotiated by Margaret Thatcher in 1980s.
But he said the European leaders' arguments have "no basis in the European treaties".
Dr Vaubel is a member of the advisory council to the German Federal Ministry of Economics and Technology, the second highest ministry of state in Germany similar to the UK Treasury.
Secession can be a positive force in western democracies, encouraging competition and improving the rights of citizens, he argues in the October edition of the journal Economic Affairs.
"The external effects of secession may well be positive. However, the political economy of secession is highly problematic," he said.
"Ideally, the rules for secession should be set at the international level but international organisations have a vested interest in preventing secession.
"The opinion of the European Union institutions that Catalonia and Scotland, after seceding, would have to reapply for EU membership has no basis in the European treaties. Nor has this question been settled in any UN agreement or Vienna Convention.
"Secession strengthens competition among governments. By putting the politicians and bureaucrats of different countries under competitive pressure, secession improves their performance. They grant more freedom to their citizens, and they are more efficient and innovative."
Any potentially negative consequences of secession, such as rising taxes due to diminishing economies of scale, may be offset by the increased democratic representation citizens achieve in a smaller state.
"I conclude that the spillover effects of secession on others are on balance more likely to be positive than negative," Dr Vaubel said.
"In Western democracies, the expected value of secession is positive, and the risks are not too large."
International organisations "have a vested interest in centralisation" and "are biased against secession".
He said: "The legal position taken by Barroso, Reding and van Rompuy has no basis in the European treaties. Nor is there a precedent in EU law. Nor does the UN Charter envisage dispositions with regard to secession.
"The treaties are also consistent with automatic succession of both the seceding state and the rump state.
"Why do Barroso, Reding and van Rompuy prefer the exclusion and re-accession of Scotland?
Citing evidence from other academics, he suggests that "the EU institutions want to renegotiate the terms of Scottish membership: Scotland would be asked to join the euro and the Schengen Agreement, and it would have to give up its part of the 'Thatcher rebate'."