How were they ignoring Article IV, Section 2. A fugitive today, or a white fugitive then, had protection of habeas corpus, the right to an extradition hearing, the right to legal counsel, the right to fight that extradition. Are any of those violations of Article IV, Section 2? Of course not, but when the Northern states tried to grant those same rights to runaway slaves the Supreme Court struck them down. And when the Northern states refused to assist in the enforcement of the fugitive slave laws, as the Supreme Court ruled they were not required to, then the southern states claim it as a lame excuse for rebellion.
FYI, Massachusetts' personal liberty laws included the following:
And? Are you saying that the commonwealth did not have the power to regulate their attorneys?
It is no wonder that many Massachusetts attorneys and judges thought the law was unconstitutional.
The unconstitutionality lay in the fact that such laws had been struck down by the Taney court before, and would no doubt be struck down again. Every law passed in recent times severely limiting a woman's access to abortion has been struck down, but that doesn't stop states from trying.
From Article IV, Section 2 of the Constitution:
No Person held to Service or Labour in one State, under the Laws thereof, escaping into another, shall, in Consequence of any Law or Regulation therein, be discharged from such Service or Labour, but shall be delivered up on Claim of the Party to whom such Service or Labour may be due.
IMO, by passing laws that in effect discharge the escaped slave from service or labor or labor for his master and preventing the slave from being delivered up on claim of the owner, Massachusetts was in violation of the Constitution.
The last slave returned from Massachusetts was in 1854. The Massachusetts personal liberty laws were passed in 1855.
Now for the rest of the story. The Kennebec (Maine) Journal reported on March 8, 1861 the following:
Refusal to Repeal the Massachusetts Personal Liberty Laws
The joint special committee of the Massachusetts Legislature, to whom was referred so much of the governor's message as relates to that portion of the several statutes regarding personal liberty, and also the petitions and remonstrances of divers [sic] persons for and against the personal liberty laws, so called, having carefully considered the subject, report certain amendments, but refuse to advise appeal of the bills in question, believing they were intended to be constitutional.
Massachusetts. The home state of Benjamin Butler.