I have a question on the laws.

If declarer claims and the defenders agree, does the declarer have the right to see the defenders' hands?  There are two reasons for wanting to do this:

--- to check to make sure there was no irregularity

--- to help evaluate how good the result on the board will be

The only discussion I could find about looking at unplayed cards is Law 66D

   After play ceases, the played and unplayed cards may be inspected to settle a claim of a revoke, or of the number of tricks won or lost; but no player  should handle cards other than his own. If the Director can no longer ascertain the facts after such a claim has been made, and only one side has mixed its cards, the Director shall rule in favour of the other side.

But this seems to require suspecting a revoke (which, of course, one generally would not) or dispute on number of tricks taken,  and does not address the second reason.

It has never been the case that defenders have not shown me their hands if I requested, but I am wondering if it an absolute right.  If so, what Law applies here?