I spoke with a colleague today about interviewing and we were both in agreement that not being able to look up answers/solutions to problems is not a good way to interview. Really takes away from the real-world experience of a developer. I wear out that Google search bar on a daily basis so why would we expect others to be able to recall information from their heads when it can easily be searched for.
On another note, should they be able to use pre-built solutions like libraries or frameworks to solve problems. Again, I'm of the yes attitude. Providing an existing solution is something we do all the time in our day-to-day jobs.
Can't wait to hear what you think!