Do you think journalists should have the right to protect their sources? describe one instance where this right would benefit society and one instance where it might be harmful?

The hardest part would be defining national security. Journalist's want to protect their source in order for the source to feel secure and not put in harm's way.

I think many journalists take advantage even when the source doesn't require protection.

How do you distinguish between the two?

I agree that for the sake of security and even solving vicious crimes, they need to reveal the source and also the source needs some form of protection.
When including the public in any reveals, they must be absolutely sure.

We, the people, have the right to information, however; the timing of the release is critical.

We live in different times. Our enemies are both inside and out of our country.