律

Step radical on the left - pictograph of a small footprint, the abbreviated form of 行 (walk). Laws and rules govern how people move through society: where they may go, what path they may follow. Same radical anchors 律 with 行 walk, 往 go toward, 待 wait; 律 is its rule.

Right side 聿 pictures a hand gripping a brush - the original character for 'writing'. Supplies the sound: yù → lǜ with significant Old Chinese drift. Carries strong semantic weight: laws are written with a brush. Step radical + brush = 'how the conduct is to be inscribed' - the original sense of 律 was a written code of conduct.