Yeah, and it was considered one afterward, too. Right up until November 1, 1864, when they abolished it. And by Constutional rights, do you mean the right to repudiate the Constitution and take up arms against the United States?
By chance in your Constitution do you happen to see anything in there referring to habeous corpus? Moreover, when was Maryland planning to take up arms?
FYI
Section 9, Clause 2 of the U.S. Constitution.
"The privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it. "
(AT THE TIME MARYLAND was not IN REBELLION and NO INVASION had taken place. )