Alright, I am a lawbringer main and close to getting to rep 30 - currently rep 24 and 44 total - so I think I got some knowledge on the subject.
The thing that is the biggest issue with the art of battle right now is that some characters like Kensei or Lawbringer have no way to open turtles that are good enough to block everything you throw at them.
Won't write anything about kensei here since I haven't even gotten him to rep 1.
Lawbringer however is a different story. How do you open a turtle? By having a vortex, basically something you need to make a guess on in order to escape it or roll out of. Some people don't like vortexes, but it's the only way to open turtles. If for some reason the design choice is made law shouldn't have a vortex remove vortexes for all other characters as well.
The core of this fix is making long arm feintable. This won't make him much stronger in dominion (removing the ability to spam it actually nerfed his dominion prowess a bit). Also LA is probably his most iconic move and it won't change his identity as a disable much. This would mean he could either:
Long arm into heavy, if they don't dodge.
Feint Long arm, grab their dodge into heavy.
Feint Long arm, parry their dodging attack, either do a gb+heavy or one of his parry follow ups.
Feitn Long arm, parry their light attack they do to interrupt long arm.
Feint Long arm, do nothing, dodge out of their dodging bash or counter the follow up vortex they could launch.
And probably a few more options. Of course, if the law guesses wrong he gets punished.
Also all those heavies guarantee a bash so instead of doing a long arm he could mix it up with heavy - heavy to get the unblockable - or light+top heavy+light for the high damage combo.
Bashing off Block would remove the 3rd option since you gain enough frame advantage. Same with bashing after a dodge.
Other small changes:
Give him more stamina. Warden can vortex you for ages, law wouldn't be able to do that. I think Warden has a little too much stamina and Law a little to little.
Remove the glitch that makes you flicker a GB into Long Arm by pressing GB a tiny bit before move back. This also works for demon's embrace btw. The fix for this would be to simply change the input to HOLD move backwards FIRST and then press GB.
Make rolling more costly overall so other characters can't keep turtling by rolling out of this vortex forever.
Remove the - most likely unintended - feature that law can get a guaranteed light after bash if he attacks in the same direction the other character was guarding last. This only works against characters with a permanent guard. Getting guaranteed damage for blocking is going to make the turtle meta even worse.
Make Blind Justice feintable, like every other unblockable, so that it is worth doing after parrying a heavy. Also making it uninterruptible might be worth a try. Blind Justice should also act as a combo starter to get the HLHL combo more easily. And you should be able to bash after Blind Justice.
Make the bash after the heavy you do after Long Arm guaranteed and not dodgable so he can continue his vortex.
This would keep his identity as a counterattacker and disabler but make him just as powerful as warden in a 1v1 if you balance stamina, defense and attack correctly. I don't want to do the math on this here, that's not my job. I could do it but you guys over at Ubi surely have professional mathematicians that can calculate the correct values for damage, defense and stamina so every character and his rock/paper/scissors vortex do the same damage on average and consume the same stamina on average.
Also his heavy-light-heavy-light combo needs to be landed more consistently. Maybe making the light after bash guaranteed isn't that bad of an idea, as long as this doesn't apply to the bash off block.