Judges deliberated for four hours, and also ruled they did not need to hear evidence from the woman at the centre of the case – Karima el-Mahroug.
Ms el-Mahroug, nicknamed Ruby the Heart-stealer, had appeared in court after failing to show on two previous dates.
Berlusconi, who is heading a centre-right coalition in the February 24-25 elections, is accused of paying for sex with her when she was 17, and then trying to cover it up. Both deny sexual contact.
Ms el-Mahroug had been the last witness, meaning a verdict could come before the elections.
Berlusconi's defence lawyer had requested the suspension of proceedings, citing the demands of the election campaign. The prosecution opposed the request, arguing Berlusconi is not the formal head of his party nor its official candidate for premier, and he has infrequently shown up for trail anyway.
In their ruling, the judges said Berlusconi's absences for a political campaign were a personal choice and could not be compared with having a parliamentary obligation.