The case in which Sarkozy was charged on Wednesday with corruption, influence peddling and violation of legal secrecy related to his alleged attempt to interfere in judicial proceedings investigating allegations his 2007 election campaign was partly financed by illicit donations from Libya's former dictator Muammar Qaddafi.
Sarkozy is suspected of seeking inside information from a magistrate at the Court of Cassation (an appeal court that rules on points of law) in return for help in securing the magistrate a lucrative job in Monaco.
The magistrate, Gilbert Azibert, did not get the posting but has also been charged along with Sarkozy's lawyer Thierry Herzog.
The crimes Sarkozy is accused of carry a theoretical maximum of ten years in prison but legal experts say a custodial sentence is unlikely in the event of a conviction.
Cash from Qaddafi?
Judges have, since April 2013, been examining allegations that former Libyan strongman Muammar Gaddafi's regime helped finance Sarkozy's 2007 campaign. Sarkozy says the claim is ridiculous and is suing Mediapart, the website which first reported the alleged $50 million payment, for defamation.
Judges authorized the unprecedented step of tapping the phone of the former president as part of the investigation. The taps formed the basis for the investigation which led to Wednesday's charges.
The Bettencourt affair
Relates to allegations Sarkozy's UMP party accepted illicit payments from the L'Oreal heiress Liliane Bettencourt for his 2007 campaign, much of it in cash-filled envelopes. Sarkozy was cleared last year of taking advantage of the elderly woman while she was too frail to understand what she was doing.
His campaign treasurer is one of ten people awaiting trial in the case.
2012 election funding
A criminal investigation was opened last month after it emerged that more than €10 million ($13.6 million) spent in support of Sarkozy's 2012 campaign had been fraudulently passed off as UMP party expenses.
Sarkozy denies any knowledge of, or role in, the apparent fraud which meant his campaign spent nearly 50 percent more than it was legally entitled to.
UMP leader Jean-François Copé was forced to resign over the issue because of his close links to the company, Bygmalion, which organized the events and has admitted falsifying bills.
The Karachi affair
Long-running investigation in which two former Sarkozy aides have been charged by judges investigating alleged kickbacks on a Pakistani arms deal concluded when Sarkozy was budget minister.
A shell company was allegedly used to channel kickbacks to then prime minister Edouard Balladur's unsuccessful 1995 presidential bid, which Sarkozy helped run.
Magistrates are also probing whether a 2002 Karachi bombing that killed 11 French engineers was revenge for the cancellation of bribes secretly promised to Pakistani officials.
A criminal investigation is ongoing over a controversial €400-million ($557-million) payout by the French state to tycoon Bernard Tapie in 2008.
Judges are looking at whether Tapie received favourable treatment in the case as a reward for supporting Sarkozy in the 2007 presidential election.
The diaries seized in the Bettencourt case may contain evidence of the regularity of Sarkozy's meetings with the tycoon at the time of the arbitration.
Five people, including Tapie, have been charged with conspiracy to commit fraud and IMF chief Christine Lagarde, who was finance minister at the time, and Claude Gueant, Sarkozy's former right-hand man, have both been questioned in the case.
A criminal investigation is ongoing into the management of contracts for opinion polling carried out during Sarkozy's 2007-12 term as president.
The probe was triggered by anti-graft organization Anticor, which says the contracts were handed to political cronies without any tender process, and that public funds were used to carry out party political electoral research.