How we cite our quotes: (Clause.Sentence)
Quote #1
No "scutage" or "aid" may be levied in our kingdom without its general consent, unless it is for the ransom of our person, to make our eldest son a knight, and (once) to marry our eldest daughter. For these purposes only a reasonable "aid" may be levied. (12.1-2)
They gave the king three examples of reasonable taxes, what unreasonable taxes do you think he was collecting?
Quote #2
The city of London shall enjoy all its ancient liberties and free customs, both by land and by water. We also will and grant that all other cities, boroughs, towns, and ports shall enjoy all their liberties and free customs. (13.1-2)
It seems like this might cause some problems between city leaders and the king, perhaps it's too vague? For clarification they'll need to refer to other ancient texts that are just about London.
Quote #3
Every county, hundred, wapentake, and tithing shall remain at its ancient rent, without increase, except the royal demesne manors. (25.1)
All in favor of rolling back rent prices to what they were in ancient times raise your hands. And remember that back then rent and taxes were basically the same thing.
Quote #4
All merchants may enter or leave England unharmed and without fear, and may stay or travel within it, by land or water, for purposes of trade, free from all illegal exactions, in accordance with ancient and lawful customs. (41.1)
The lawful custom here is to not tax merchants to the point that they couldn't afford to come to England anymore. Hey, that seems fair.
Quote #5
All barons who have founded abbeys, and have charters of English kings or ancient tenure as evidence of this, may have guardianship of them when there is no abbot, as is their due. (46.1)
It's okay to exploit people and institutions, but only if you're following ancient customs that have been around so long they don't make much sense anymore. (This isn't one of the clauses that's stood the test of time.)