What are some theories that currently can't be tested due to ethical problems?

Asking for a friend.

Joking aside, I've been thinking about globalization and how society would react if north korea, for example, decided to further science without much regard for ethics when I realize I have no idea what kind of knowledge could possibly lie behind those doors and I got curious :)

edit: I tagged this post as What If because it kind of is, but I'm unsure if this is how this tag should be used. Is this OK?