They want the witness for the Economic and Financial Crimes Commission (EFCC), Mr Owobo Tosin, to be disqualified from testifying in their trial.
The objections were raised at the resumed trial of Amosun and 10 others, charged by commission on 23 counts bordering on the offence.
Amosun was charged alongside two other officers of the Air Force – Air Vice Marshal Jacob Adigun and Air Commodore Gbadebo Olugbenga.
Also charged were Delfina Oil and Gas Ltd, Mcallan Oil and Gas Ltd, Hebron Housing and Properties Company Ltd, Trapezites BDC, and Fonds and Pricey Ltd.
When the case was called on Wednesday, the prosecutor, Mr Rotimi Oyedepo, commenced examination of the witness, an investigative officer with the commission.
Abruptly, Amosu’s counsel, Mr Bolaji Ayorinde (SAN) raised an objection to his testimony.
His objection was premised on the failure of the anti-graft agency to attach the statement of the witness to the proof of evidence.
According to him, the witness will only be competent to give any evidence in the matter when copies of his statement are served on the accused by the EFCC.
Citing the provisions of Section 379 of the Administration of Criminal Justice Act (ACJA) 2015, the silk said it was mandatory for any witness who is to give evidence to have a statement.
He said the non-availability of the witness statement was a gross violation of the accused person’s right to fair hearing as enshrined in the Constitution.
He then urged the court to disqualify the witness from testifying in the matter.
Oyerinde’s position was also adopted by other defense counsels.
In response, Oyedepo maintained that the only time a witness can be disqualified by the court is when he cannot understand questions.
According to him, the proof of evidence served on the defense as far back as June 2016 substantially complied with the provisions of Section 379 of the Administration of Criminal Justice Act (ACJA) 2015.
He added that it was wrong to be asking for the statement of an investigative officer because he was merely investigating an incident.
Justice Mohammed Idris fixed Nov. 24 to deliver his ruling on the issue.
The accused were arraigned on June 26 and had pleaded not guilty to the charges.
The judge had then granted them bail in the sum of N500 million each with two sureties each in like sum.
The charges against the accused bordered on conspiracy, stealing and money laundering.
In one of the counts, the accused were said to have indirectly converted the sum of N3.6 billion belonging to the Nigerian Air force, to their own use.
In another instance, the EFCC alleged that Amosun and the others stole over N323 million from the accounts of the Nigerian Air Force between March 21, 2014 and March 12, 2015.
He said the alleged theft was for the purpose of purchasing for themselves a property situated at No.1, River Street, Wuse II Abuja.
The alleged offences were said to have contravened the provisions of Sections 18 (a) of the Money Laundering (Prohibition) (Amendment) Act, 2012.