The Law staff is a magic weapon, released with the Dungeoneering update, on 12 April2010. It costs 10,000 Dungeoneering tokens. Players can store up to 1000 law runes within it, and when used it has a 1/10 (10%) chance of not using a law rune. As a melee weapon, it is tied as strongest staff available in Free-to-play with the nature staff. The gravite staff has a stronger magical attack bonus. Strangely the inventory icon is upside down of how a player holds it.
The following is a comparison of the cost per cast of spells using Law runes while using an elemental staff as opposed to using a Law staff. The cost per cast when using the Law staff is approximate and assumes that exactly 1 out of 10 Law runes are saved.
Example on reading the table:
The cost of Varrock teleport using a Fire staff is 284 gold.
The cost of Varrock teleport using a Law staff is 339.9 gold.