Well, they can't, but they do. That is why they get opinion letters from dead attorneys, or forged opinion letters. Sometimes even dubious attorneys will look the other way for a pay check.
That is why the sellers get litigated for 144 abuse, CEO's get C&Ds, companies get suspensions, counselors get disciplinary actions by their state bar, and chills or global locks are put in place.
But they have to commit the offense before the aforementioned actions can occur, unfortunately.