“The king also derived money through the granting of monopolies, despite a statute forbidding such action, which, though inefficient, raised an estimated £100,000 a year in the late 1630s.”
https://en.m.wikipedia.org/wiki/Charles_I_of_England
Although with the UK system being (especially at that time) based on unwritten traditions over actual black letter law makes it easier to argue that he was violating more the spirit than the black letter law but his attempts to bypass Parliament’s taxation powers via every loophole he could find, legal, extralegal and sometimes outright illegal.
Of course that was not the only matter of dispute, the religious ones being just as critical (and in that case you can not prove who was objectively right or wrong because it was theological) but his attempting to bypass Parliament was quite a problem, and obviously Parliament would not like that and try to stop it.