The Law of Color means:

brands should use a consistent color scheme in all marketing $($e$.$g$.,$ UPS is always brown$)$

that all colors have strong cultural symbolism $($e$.$g$.,$ green$=$healthy$)$

it's best to use a color scheme that is the opposite of your main competitor

it's best to use colors that fit in with the category $($e$.$g$.,$ dark blue $=$ accounting firms$)$

bright colors sell more products