Until the annulment, Kalu was the Senator representing Abia North at the National Assembly.
The tribunal also ordered a rerun election for the Abia North Senatorial District.
Kalu was elected on the platform of the ruling All Progressives Congress and was inaugurated as federal lawmaker for the 9th National Assembly.
Last Thursday, the tribunal had dismissed a petition brought before it by another individual — the candidate of the All Grassroots Alliance, Anagha Anagha, challenging Kalu’s victory in the Abia North senatorial zone election.
Anagha had challenged Kalu’s victory on the ground that he (Anagha) was excluded from contesting the election by the Independent National Electoral Commission.
But the three-man tribunal led by Justice Cornelius Akintayo, in a unanimous judgment on Thursday, ruled that the petitioner had failed to prove his allegation of exclusion by INEC.
The tribunal also held that Anaga did not have anything to prove that he was a candidate in the election and therefore had no locus standi to challenge the election.
The election tribunal therefore scolded the petitioner’s lawyer for bringing the case to the court in the first place without ascertaining that his client was a candidate of AGA for the election.
The tribunal awarded a cost of N500,000 against him in favour of the respondents.
The tribunal had earlier granted an application by AGA, seeking to strike out its name from the petition on the grounds that the petitioner was never nominated by the party.