Spain has suspended visa-free travel and reinstituted border checks ahead of a meeting of the European Central Bank.
It is an unprecedented move that over-rides the Schengen Protocol that was first instituted in 1985.
The agreement means there are no internal border controls for 26 European countries and a population of more than 400-million people.
Spain says it needs to regulate its borders to prevent foreign protesters disrupting the ECB meeting in Barcelona next week.
It is not the first time Schengen has been called into question - Germany and France also want new rules to make it easier to suspend passport-free travel.
Sonia Gallego reports from Madrid.