Perhaps the thorniest issue involves who will pay for the new technology.

Isn't that a thorny issue for some people, letting the child see your income?

Then there is the thorny issue of the 100,000 residents without cars.

But getting more specific than that raises some thorny issues, he said.

That thorny issue has yet to be decided, people involved in the discussions said.

There is still the thorny issue of what to call these vehicles.

Those are the very important and thorny issues which must be dealt with.

This is therefore one of the thorny issues we need to address.

That can certainly be a thorny issue, and what comes out at the end is not always rigorous.

Still another thorny issue is the "too big to fail" policy.