The man who sparked the chain of events that led to the downfall of Deputy Prime Minister Barnaby Joyce says more MPs will likely fall.

Western Australian lawyer John Cameron exposed Greens MP Scott Ludlam as a New Zealand citizen in July this year, leading to an eventual constitutional crisis for the federal government.

Senator Ludlam's resignation resulted in the status of numerous other politicians being questioned, which culminated in Friday's High Court Decision disqualifying five federal MPs.

While Mr Cameron said he was "invariably surprised" at how quickly the citizenship scandal had snowballed, he expects more politicians will fall foul of section 44 of the Australian constitution in coming months.