Perhaps the most dangerous issue for the government over the EU (Withdrawal) Bill has been the sweeping "Henry VIII powers" it gives to ministers to re-write 40 years of accumulated EU law so that it will still work after Brexit - this is law on everything from employment rights to the environment - so if it was suddenly unworkable, real problems would follow.
Conservative backbenchers led by the former Attorney General Dominic Grieve have put down amendments to the bill to provide for a "sifting mechanism" which would look at proposed changes made under this legislation and flag up any which deserved more debate.
Most of the changes would be under a mechanism where they would not be discussed - which could, potentially, allow major changes to go through without parliamentary scrutiny.
The Commons Procedure Select Committee has been looking into the issue and is now putting forward its own amendments to the bill.
They would create a special committee of MPs to do the sifting - and it will have the power to recommend more debate on contentious changes.
Committee Chair Charles Walker said the proposals had cross party backing and were "a fantastic triumph".
"There was great concern that the secondary legislation coming out of the bill would be pushed through on the nod - this will ensure it will not happen like that."