A law expert believes creating controls around terror content online doesn't equate to putting up a brick wall on technology.

University of East Anglia IT law expert Paul Bernal told Mike Hosking the problem is platforms want to offer people services they will use in a nice way.

"Business models are technology without much human intervention - so they're slow to react when something bad happens. And when they do, it's too late.

"They could deal with a lot of concerns which people have brought up, but it would complicate how they operate enormously."

Bernal says Facebook could quite easily make changes to ensure incidents like the live-streaming of last Friday's Christchurch mosque attack don't happen again.

"The problem is they want to offer services to people in a nice way. Their model is based mostly on technology with not a lot of human intervention. They are quite slow to react because their systems don't catch it. Even though they acted as quickly as they could, it wasn't quick enough.

"They can't really control it if they want to offer a service which people can use immediately and sufficiently."