RW> I don't think so.  Look at drivers and marriage
 RW> license.  The rules for obtaining these license vary
 RW> from state to state but they are honored in ALL states.
 RW> Now if the congress tries to set minimum requirements
 RW> for the states or says that a TX license holder only
 RW> had to follow TX law in CA then the 10th would come
 RW> into play.
PN>  To what degree do we want to insist that states recognize
PN> other states'  licensing?
Most, if not all, of them.
PN>  Drivers and marraige licenses are obvious.  What about
PN> other forms of  licensure such as professional licenses:
PN> attorneys, barbers, doctors? 
Yes to all.  Unless you think some state is licensing a
quack!  Just do them like DL's, if you are in the state
temporarily then they are honored.  If you are or
become a permanent resident then you have to acquire a
license from that state. 
The only one of the three you mention that I might have
a prob with would be the attorneys.  And that is
because the laws vary so much from state to state.  But
any lawyer worth his salt should be able to research
the laws of the state and be able to defend you so it
isn't a strong argument.
IMO, the only reasons states don't honor those licenses
from other states is MONEY and politics (that could be
the same as money).  I live near Ft Campbell.  Although
it's called Ft Campbell Kentucky but it sits across the
state line and most of it is in Tennessee AND the
closest major town is Clarksville, TN (right outside
gates 1, 2, & 3 with a pop of over 75K).  I know a lot
of medical personal (RN's, LPN's, EMT's, MD's, etc.)
some of them work in all three areas (the Fort, KY &
TN) now to this they have to have three licenses.
Which means that they have to take both states test and
pay both states licensing fee. 
PN>  Perhaps it would be better to stop requiring so many
PN> activities to be  "licensed."
Here, here.
                      Remember:  Freedom isn't Free!
--- timEd-B11
---------------