The anti-graft courts special division yesterday ordered the 40-year-old former San Juan mayor to post a P100,000 travel cash bond.
Estrada was given permission to stay in California up to Monday, June 14, following his weekend talk.
In allowing Estradas travel, Justices Edilberto Sandoval, Teresita Leonardo-de Castro, and Ma. Cristina Cortez-Estrada said the evidence against him is not strong that he was granted bail at P500,000.
"It is not only nil but practically non-existent," the justices said in a four-page resolution, referring to the governments fear that Estrada is a flight risk or that he could avoid prosecution of the plunder charges against him.
The justices said Estradas travel to California does not bring with it risks or any concern with regard to national security, public safety or public health.
"The mantle of the presumption of innocence still covers him," the resolution said.
The justices said they also recognize the governments argument that Estradas election as a senator will not affect the criminal case against him, and that the trial will proceed as scheduled.
"In fact, the trial continues," the resolution said.
"We are in full agreement with the prosecution that the fact that he has been elected does not alter the truth that he is still one of the principal accused," it said.
Retired Manila fiscal Jose Flaminiano, one of Estradas lawyers, said his client was invited by organizers of Fiesta Filipina, one of the largest Philippine Independence Day celebrations in North America.
Special Prosecutor Dennis Villa Ignacio has opposed Estradas request on grounds that the government has a pending petition before the Supreme Court to cancel his bail.
Estrada was granted bail by the special division in March last year.