Rule of Law
If you destroy it does that allow you to play as many cards as you can on that turn or do you finish that turn out with only being able to play one card?
Rule of Law's effect lasts only while Rule of Law is on the battlefield, because the effect comes from a static ability (C.R. 611.3b, 611.3, 113.6, 604.1). Once Rule of Law leaves the battlefield, each player can cast more than one spell each turn as normal. (If a continuous effect from a static ability is meant to continue even after the permanent leaves the battlefield, this will be specified explicitly [C.R. 101.1], as in the ascend ability on a permanent [C.R. 702.131b] and in Titania's Song.) See also this thread.
EDIT (Aug. 15, 2022): One rule was renumbered in the meantime.
If you destroy it does that allow you to play as many cards as you can on that turn or do you finish that turn out with only being able to play one card?
EDIT (Aug. 15, 2022): One rule was renumbered in the meantime.