you would root some cuttings...

i would doubt the ability to split a shrub.. but i cant see yours.. so i dont really know ...

google: propagation of barberry ...

good to know you respect the wishes of your state bureaucrats .. lol ..

ken

I have split hydrangeas and tree peonies successfully but have never tried barberry. Cuttings may take to long for the trunk to fatten for bonsai that's why am considering splitting in the spring.
If any one has tried this I would appreciate their help.

Why don't you dig up the entire shrub, plant something that's not so environmentally damaging in its place, and maybe use the existing plant for bonsai (if you just have to have one). There's a reason that they aren't available any longer!

BTW, wouldn't these things be pure torture to use for bonsai? They are hard enough just to clean out in fall after leaf drop. The thorns are just nasty.

That's not a bad idea.
I usually Take off the thorns as the appear.
Burning bush was also banned at the same time and I had never seen a wild burning bush. What a surprise, I saw plenty of them after I was made aware that they are invasive.
Guess I just wasn't looking for them.