grey area
gray area

"I was living in the gray area of the rules."

"A lot of problems that are very gray areas need to be put in black and white."

You're willing to move right on into the gray areas.

But what you hit on about the gray areas is exactly it.

That is the grey area between health and social services.

Still it seems to be a bit of a grey area.

And how to apply one from the other is still a gray area.

These jobs must be brought out of the grey area.

And this is really a gray area of the law.

These are grey areas where common sense has to be used.