Chief Whip of the senate, Professor Olusola Adeyeye, said the Senate Standing Rules were actually altered in June 2015.
Adeyeye made the disclosure while speaking with Channels Television on Sunday, adding that the court would have to determine whether it was forged or not.
He said, "In the 7th Assembly, voting has to be done publicly (but) in this current one, it was done privately."
The Senate Chief Whip, while expressing regret over the current situation in the Red Chamber, stressed that the senators have not shown maturity in handling the situation.
He continued, "Our own rules in the Senate forbid us from discussing matters in the court.
"Those who support our Senate President (Dr. Bukola Saraki) should have given him all the support he needs so as to provide for himself, the best defence in the court of Nigeria."
Adeyeye, however, said removing the senate president, Bukola Saraki as the leader of the senate would not be possible considering the number in the Senate.
He added, "If politics is a game of number, Saraki has the number in the Nigerian Senate (and) let nobody deceive himself.
"In the current situation, it is impossible because a majority is not enough to remove him (and) by the rules of the Senate, you need 2/3 to remove a presiding officer.
"That number will not come."
The trial of the Senate President on alleged forgery of the Standing Rules opened on Monday in a Federal High Court in Abuja.
He and his deputy, Ike Ekweremadu have pleaded not guilty to the charges.