31 January 2012 Last updated at 05:44 ET
The supreme court in Spain has refused a request to throw out a case against Judge Baltasar Garzon, accused of overstepping his authority.
Spain's most famous judge is testifying at his own trial for ordering an inquiry into mass killings by forces loyal to former dictator Gen Franco.
Baltasar Garzon is accused by two groups of violating a 1977 amnesty.
He argues no amnesty can cover crimes against humanity but his critics accuse him of reopening war wounds.
Fascist leader Gen Francisco Franco ruled Spain from 1939, the end of the civil war, until his death in 1975.
Thousands of people demonstrated in Madrid in support of Baltasar Garzon on Sunday.
Politicians, prominent artists, union groups and actors joined the crowd which brandished placards saying "Garzon, friend, the people are with you" and "We demand justice".
Two organisations - Cleans Hands and Liberty and Identity - opened a civil case against Judge Garzon, who is best known outside Spain for securing the arrest of former Chilean leader Augusto Pinochet in London in 1998.
The judge also faces two other court cases on charges of dropping an investigation into the head of Spain's biggest bank, Santander, and illegally authorising police to record conversations between lawyers and clients.
If convicted at any of the trials, he could be suspended from the legal profession for up to 20 years, in effect ending his career.Robes off
Removing his judge's robes, Mr Garzon sat behind a small table in the main chamber of the supreme court to deliver his testimony in front of seven judges.
A majority of the judges ruled that the arguments put forward for dropping the case lacked "sufficient material weight".
Mr Garzon's court appearance comes as archaeologists investigate the site of a mass Civil War grave at a cemetery in the south-western town of Gerena.
Remains of 17 people, all women, were found dumped together.
They are believed to have been rounded up and shot by Franco's forces in 1937 for being relatives of people on the opposing Republican side.