The petition filed by MLA Ajay Rai, who was fielded by Congress from Varanasi in the 2014 general elections, was being heard by Justice V K Shukla.
Arguing on behalf of PM Modi, senior advocate and BJP leader Satya Pal Jain said the petition was "not maintainable" and "deserves to be dismissed with cost".
"The petitioner has failed to place on record any material facts and has simply levelled allegations on the basis of hearsay. Moreover, allegations made by him like distribution of caps bearing photographs of PM Modi pertain to the period before he filed his nomination papers on April 24, 2014.
"There are a number of Supreme Court judgments wherein it has been held that a person can be treated as a candidate only from the date he files his nomination and that he cannot be held responsible for any act of his supporters prior to that date," he said.
In the light of these facts, the petition deserves to be dismissed with costs, said Mr Jain, who is also the Additional Solicitor General of India in the Punjab and Haryana High Court.
Mr Jain, who is a member of the BJP's national executive and a former Lok Sabha member from Chandigarh, also prayed for rejecting the election petition "invoking provisions of Order 7 Rule 11 of the Civil Procedure Code" but added that he would "need two more days of hearing to complete my arguments".
Mr Rai, who represents Pindra in the state assembly, had filed the election petition in June, 2014, shortly after results for the Lok Sabha polls were declared.
A former BJP member himself, Mr Rai had joined the Congress in 2012 after a brief association with the Samajwadi Party.
Although a local, Mr Rai performed badly in Varanasi where the electoral battle turned out to be a one-sided affair with PM Modi bagging more than 50 per cent of the nearly 10.3 lakh votes that were polled.
Among PM Modi's challengers, only Arvind Kejriwal of the Aam Aadmi Party could manage to save his deposit even though he was defeated by the winning candidate by a huge margin of 3.71 lakh votes.
Mr Rai finished third in Varanasi seat, which Modi went on to retain after becoming the Prime Minister, resigning from Vadodara constituency in Gujarat where he had won with a record margin of 5.7 lakh votes.