OTTAWA - A pause has been called in the Ottawa trial of Senator Mike Duffy on breach of trust, fraud and bribery charges.

Justice Charles Vaillancourt will hear arguments Monday in what is called a voir dire, which is basically a mini-trial within the main event.

Lawyers will argue over the admissibility of a 2010 Senate report based on an audit of senators' office expenditures and service contracts .

Duffy's lawyer, Donald Bayne, wants to treat that report as fact and possible use it to prove his contention that the Senate knew its rules were vague and confusing.

The Crown, however, wants the report treated as opinion, not fact -- a key distinction when the judge later reviews the evidence.

The trial is already expected to overrun its 41-day schedule by weeks and this pause will extend the proceedings even further.