A group of Labour backbench MPs has called for the abolition of regional list members of the Scottish Parliament.
At present, 73 out of 129 MSPs are elected to represent constituencies; 56 are selected from a party list.
As the Commons considered the Scotland Bill for a third day at committee stage on 15 March 2011, Labour MP for Central Ayrshire Brian Donohoe said that the system was "crazy".
"There is no accountability for these list members," he argued, urging MPs to support a new clause to the bill which would remove the contingent of MSPs elected from party lists.
Mr Donohoe noted that by-elections are not held when list members resign, as they are with constituency MSPs. Instead, they are replaced by another candidate from the party list.
He also claimed that regional list MSPs were able to "come into constituencies to cherry-pick and cause mayhem".
The legislation implements recommendations of the Calman Commission to hand control of some taxes from Westminster to the Scottish Parliament.
The commission's final review of Scottish Devolution, published in 2009, called for Holyrood to take charge of half the income tax raised in Scotland. The new powers would be combined with a cut in the block grant which Scotland gets from the UK government - currently about £32bn.
Under the plans, MSPs would also gain control over stamp duty and landfill tax.
The UK government says the bill provides for the "biggest transfer of fiscal power to Scotland".
Scottish Nationalist Party MPs support the devolution of further powers to Scotland, but say the bill does not go far enough.
Watch part two of the debate