Activism over a royal commission into the banking sector will be played out today in the Senate, as five cross-bench senators bring on a private members' bill to set up "a parliamentary inquiry into the banking and financial services sector."Senators Whish-Wilson, Hanson, Hinch, Lambie, Roberts and Xenophon are behind the bill, a spread that suggests, with Labor support, it will pass the Senate.As a substitute for a royal commission, this inquiry - authorised by an act of parliament - must pass the House of Representatives, where it takes only one rogue MP to deprive the government of numbers to block the bill.The explanatory memorandum for the bill states that "the full extent of misconduct with the banking and financial services sector has not been discovered, particularly given the limited time and resources available to committees of the parliament, and the inability to utilise expert legal cross-examination and forensic analysis. "This Bill seeks to ensure that the extent of misconduct with the banking and financial services sector is exhaustively examined and that the impact on victims of misconduct is fully understood. "This Bill appoints a Commission to establish the causal factors for this misconduct, including misaligned incentives, culture, inadequate regulation and regulatory power, and 'moral hazard' extending from government guarantees. This issue is of concern given the size of the banking and financial services sector, and its importance to the functioning of the Australian economy."