South Korea's Constitutional Court formally begins President Park Geun-hye's impeachment trial

South Korea's Constitutional Court on Wednesday began to hear oral arguments in the impeachment trial of President Park Geun-hye, who lawmakers voted to remove over a corruption scandal that saw millions of people protest over the last several months.

Park's lawyers and lawmakers, who serve as prosecutors in the trial, traded pointed arguments on the validity of accusations that she colluded with a confidante to extort money and favours from companies and allowed the friend to unlawfully interfere with government affairs.

Lawmaker Kweon Seong Dong, the chief prosecutor in the trial, said Park betrayed the trust people put in her by "broadly and gravely" violating the constitution and criminal laws.

Park's lawyer, Lee Joong-hwan, said the accusations stated in the impeachment bill "lack evidence and fail to make legal sense" because they were based on allegations and media reports, not criminal convictions. The hearing proceeded without Park, who refused to testify for the second time following her no-show on Tuesday. The nine-justice court cannot force Park to appear.

Park's lawyers may prefer her not to testify because their chief argument is that the accusations against Park haven't been fully proven, said Han Sang-hie, a law professor at Seoul's Konkuk University. Park rejected requests by state prosecutors to question her and has yet to be questioned by the special prosecution team that has taken over the inquiry.

The court, which will hear witnesses later Thursday, has six months to decide if Park should permanently step down or should be reinstated.