Why? After all, you are going to use the internet while on the job too. Just making the problems more difficult should fix that problem.

I don't mean the interviewers should shut off internet access entirely, but what I mean is that if they do allow access to the internet, they'll need to check the interviewee hasn't just googled for the solution to their codibility test (and they'll also have to make sure the interviewee can't delete their browsing history too).

Don't worry, we have some nasty surprises for the cheaters ;)