Former French President Nicolas Sarkozy on Wednesday lost his final bid to avoid standing trial on charges of corruption and influence peddling, his lawyer said.
Sarkozy is accused of offering to help a judge win a promotion in Monaco in return for leaked information.
The case arose after investigators tapped the phones of Sarkozy and his lawyer Thierry Herzog to examine allegations that late Libyan leader Muammar Gaddafi funded Sarkozy’s successful campaign for the presidency in 2007.
As they eavesdropped on his calls, investigators began to suspect the ex-president had offered judge Gilbert Azibert a promotion in return for information on developments in a parallel investigation into allegations Sarkozy accepted illicit payments from L'Oreal heiress Liliane Bettencourt for the same campaign. Sarkozy was cleared over the Bettencourt allegations.
His lawyers have previously argued that magistrates looking into the alleged secret Libyan funding exceeded their powers and went on a "fishing expedition” by tapping his conversations with Herzog between September 2013 and March 2014, breaching lawyer-client privilege.
On Wednesday, Sarkozy's defence team said the use of wiretapped remarks gleaned for an investigation into illicit campaign financing to prosecute unrelated charges of corruption contravened a ruling by the European Court of Human Rights.
"These legal issues are still relevant," Sarkozy lawyer Jacqueline Laffont said. "It will be for the court to decide whether a French court can override a decision of the European Court of Human Rights."
Wednesday's ruling that the trial should proceed came from the Cour de Cassation, a court which decides whether an earlier decision by an appeals court conforms with French law.
Sarkozy was president from 2007 to 2012, losing office to Socialist Francois Hollande when he ran for re-election. He lost presidential immunity from legal prosecution a month after he left office and has since faced a spate of investigations into alleged corruption, fraud, favouritism and campaign-funding irregularities.
The Cour de Cassation also threw out appeals by Herzog and Azibert, who will face trial alongside Sarkozy.
The setback for Sarkozy comes only a month after France's Constitutional Council cleared the way for the former president to be tried over a case related to alleged illegal financing of his failed re-election campaign in 2012.
The so-called "Bygmalion" case against Sarkozy centres on accusations that the former president's political party, then known as the UMP, worked with a friendly public relations firm to hide the true cost of his re-election bid.
France sets strict limits on campaign spending. Prosecutors allege that the PR firm, Bygmalion, invoiced UMP rather than the campaign, allowing Sarkozy to spend almost double the permitted amount.
Sarkozy denies any wrongdoing in the Bygmalion affair and has appealed that case before the Cour de Cassation as well.
Sarkozy would be the first French leader in the dock since Jacques Chirac, who was president from 1995-2007 and was convicted of misusing public funds in 2011. Chirac, now 86, was given a suspended jail term.