The eccentric brother of the king of Belgium claims his human rights will be violated if the government goes ahead with its threat to cut his salary to €308,000 (£280,000).
The country's liberal Mouvement Réformateur administration wants to cut the endowment of Prince Laurent by around 15% following a series of unauthorised meeting with foreign leaders.
The most recent of these was when the younger brother of King Philippe of Belgium turned up in full naval uniform at the Chinese embassy in Brussels for the 90th anniversary celebration of the founding of the Red Army in July.
But in a seven-page letter to the Belgian prime minister Charles Michel the prince's lawyer claims the pay cut would run "contrary to the most fundamental rights of the human person in a developed society", reported newspaper La Libre.
The letter argues the cut amounted to a breach of article eight of the European convention on human rights as it would force him into "social isolation".
Supporters of the prince say that according to custom he is not allowed to draw social security or belong to a pension scheme. They add the 53-year-old is also not allowed to work in any recognised professional, and so relies on his government salary.
MP Hendrik Vuye, who is usually an opponent of the monarchy, said today (1 November): "The prince, like any citizen, has the right to defend himself, and certain aspects of the law are contrary to the European Convention on Human Rights."
The prince's legal team also point out "that no diplomatic damage" had been sparked by any of the royal's impromptu meetings.
Supporters of the prince say instead of the pay cut an agreement could be reached where the royal would give ten days' notice of any intended meetings with foreign officials.
However, prime minister Michel said he has repeatedly explained his responsibilities to the prince, whose wife Princess Claire is from Bath, southwest England.
Last year Prince Laurent was forced to repay €16,000 to the Belgian state for claiming expenses for a ski holiday, supermarket bills and the school fees of his three children, after a critical report from the national auditor.
In 2011, the royal lost his driver's licence after being caught speeding through Brussels in his Fiat Abarth Punto. At the time he said there should be "a special licence for those driving a fast car".