Matt Bellamy, frontman of Muse, was among those to criticise Leicestershire Police for scanning the faces of music fans at Download festival in June.
It was done as a trial as a method of identifying known criminals.
Chief Constable Simon Cole said parliament needs to decide "what is OK or not".
"For me it's an area where technology has advanced probably quicker than legislation," he told BBC Radio Leicester.
"The Police and Criminal Evidence Act was written in the 1980s - this kind of technology existed in science fiction films at that point and now it exists in reality.
"The law needs to change to take account of that."
Matt Bellamy criticised Leicestershire Police during his band's performance at Download.
He used an expletive and referred to how the force was "scanning your faces".
Rachel Robinson, a policy officer for human rights group Liberty, said: "We really think that there's a real need for caution here.
"The police [need] to think about their relationship with their communities and the broader impact that this kind of mass surveillance can have."
The use of facial recognition technology at Download was a trial, but Leicestershire Police routinely uses the NeoFace system to compare suspect images against the 92,000 faces on the force's database.
Mr Cole said this helps them identify suspects more quickly than traditional methods.
The force's database contains faces of everyone who has been photographed in custody - including those who turn out to be innocent.
"As the law stands at the moment the Police and Criminal Evidence Act says we can keep those photos," said Mr Cole.
"At the moment it's everybody [photographed in custody] and that's one of the discussions that's ongoing, and we are involved in those discussions nationally, because parliament needs to decide whether that's OK or not."
A police force criticised for its use of facial recognition software has said the law needs to change to catch up with technology.