Lawyers for former Chilean President Augusto Pinochet are fighting a court ruling that he is fit to stand trial for alleged human rights abuses.
Families of the victims were overjoyed at Judge Guzman's ruling
They scored a minor initial victory when an order to place the 89-year-old under house arrest was suspended.
Victims' families celebrated as Judge Juan Guzman's ruling brought him a step closer to trial on charges of murder and kidnapping during the 1970s.
But Gen Pinochet's lawyers say he is being persecuted.
They are now appealing against the substance of the ruling.
The charges relate to the murder of one Chilean and the disappearance of nine others as part of Operation Condor - a conspiracy by six South American regimes in the 1970s to hunt down and kill their left-wing opponents.
Viviana Diaz, president of the Association of Relatives of Disappeared Persons, told the Associated Press news agency that it was "a historic decision that must be celebrated by all democrats".
She added: "This is great news for all those Chileans who do not accept impunity in the violations of human rights."
Mrs Diaz later led a march of celebration along the main street of Santiago.
But lawyers for Gen Pinochet called Judge Guzman's ruling illegal.
"This is no more than a new episode of the most relentless
persecution this country has ever seen against one person,"
said Pablo Rodriguez, one of his legal team.
The BBC's Clinton Porteous in Santiago says they appear to have won a minor victory with the suspension of the house arrest order.
Judge Guzman said he made his decision to charge Gen Pinochet after studying an interview that he gave to a Miami TV channel in November 2003.
In it the former leader said he saw himself as "a good angel", and blamed abuses during his years in power on subordinates.
The judge said that the interview, in which the general gave apparently lucid answers to questions, was "one of the elements taken into consideration" in his ruling.
PINOCHET TRIAL TIMELINE
October 1998: Police in UK arrest Pinochet on Spanish warrant; long legal battle over fitness for trial
March 2000: Deemed unfit for trial, returns home; days later effort begins to try him in Chile
August 2000: Supreme Court strips his immunity; later declared fit to stand trial
July 2001: Charges suspended and later dropped on grounds of health
May 2004: Court strips Pinochet of immunity from prosecution over fresh charges
Earlier this month, a court ruled that Gen Pinochet could face charges over the murder of his predecessor as army chief, Gen Carlos Prats, who died in a car bomb attack in Buenos Aires in 1974.
Gen Pinochet is also being investigated over tax fraud and money laundering.
The Supreme Court only decided to strip the former leader of immunity from prosecution in August. But so far the state of his mental health has prevented him from standing trial.
A previous investigation, accusing him of responsibility for the deaths of more than 70 political prisoners, fell through in 2001 when an appeal court found that he was too unwell to be tried.
He has previously been diagnosed with "moderate dementia", while doctors have disagreed over whether or not he is fit for trial. He also has diabetes, arthritis and uses a pacemaker.
A Chilean inquiry concluded that more than 3,000 people were killed for political reasons during Gen Pinochet's rule, while more than 30,000 Chileans have testified that they were tortured or detained by the military government.