HSBC Whistleblower in Spanish Court Over Swiss Extradition Request
The hearing is due to start at 0800 GMT. It is not clear when the judge will issue his ruling although two judicial sources said it should happen within the next few days - and possibly as soon as on Tuesday.
Falciani, a French citizen who worked for HSBC's Swiss private bank, in 2008 leaked details of thousands of clients, many of whom he suspected were using their accounts to evade tax at home - information that sparked investigations in several countries.
Hailed as a hero by some, Swiss courts sentenced him in absentia to five years in jail.
Falciani was arrested in Madrid at the beginning of April while on his way to speak at a conference on whistleblowing in the Spanish capital.
France, Austria, Belgium, Spain and Argentina launched investigations based on the information leaked by Falciani, but Swiss authorities insist the data was stolen and therefore legally inadmissible.