In this model, the MICR information on a check could be transmitted over a dedicated network or, as recently suggested by some bankers, the ACH. 2  Check 21 removed legal barriers that were preventing electronic technologies from being applied to long-established checkcollection processes.
Before Check 21, a bank had to present the original paper check to the paying bank unless the paying bank had agreed to accept presentment of the check electronically. While Check 21 did not mandate the electronic processing or presentment of checks, it did authorize a new negotiable instrument, called a substitute check, which is the legal equivalent of the original check.