Members of the 23-person Senate will sit as judges to determine whether Supreme Court Chief Justice Renato Corona should be removed from his post and become the highest-profile scalp yet in Aquino's relentless anti-graft drive. "I think this is a momentous occasion in our political history, which we should all be closely watching," court spokeswoman Valentina Cruz told AFP, pointing out that the head of the judiciary had never before been sacked. Aquino won a landslide election victory in 2010 largely on a platform to end the corruption which has plagued the Philippines for decades and which he says got worse under the decade-long reign of his predecessor, Gloria Arroyo. Arroyo was arrested in November last year on charges of rigging the 2007 senatorial elections and is now awaiting trial in a military hospital where she is being treated for what she says is a rare spinal injury. Aquino then marshalled his allies in Congress to impeach Corona last month largely over allegations that as top judge he had tried to protect Arroyo from prosecution. Arroyo appointed Corona, her former chief of staff, to the top judicial post shortly before she stepped down as president in a move that Aquino said ignored a constitutional ban on "midnight appointments" by outgoing leaders. Public opinion polls show Aquino enjoys overwhelming backing for his anti-graft efforts, though his critics and even some supporters say he has been employing unnecessarily bruising tactics. Some have also accused him of overstepping constitutional boundaries while going after Corona, and said his attack on the chief justice has dangerously weakened the independence of the judiciary. The Philippines has a turbulent recent history of dictatorship, revolutions and military coup attempts, and critics have warned Aquino may be raising political tensions to a dangerous level. Aquino and his team insist they have broken no laws and say tough action must be taken against high-profile perpetrators to crush the culture of impunity that allows corruption to flourish. Presidential spokeswoman Abigail Valte said the impeachment trial was evidence of "a vigorous democracy at work" and showed the government was prepared to use the law to hold public officials to account. The military has so far stood behind Aquino, who has launched wide-ranging reforms in the armed forces and promised to jail corrupt officers. The varied backgrounds of some of the senator-judges who will decide Corona's fate reflect the colourful side of Philippine politics. Among them are ex-dictator Ferdinand Marcos' son, the strongman's old defence minister, two former failed coup plotters, an ex-police chief once accused of murder, three former action movie stars and a comedian. Corona has enlisted the help of the country's legal luminaries to defend himself, including a retired Supreme Court justice, who will be pitted against an 11-member prosecution team backed by 59 volunteer private prosecutors. The prosecutors have said they would like to wrap up their case in three weeks, in an effort to achieve a quick ruling. But Cruz said it could take longer given the amount of documentary evidence to be presented by both sides. The trial is scheduled to start at 2:00 pm (0600 GMT).