Dead to Rights Cheats

Cheat List
Harder Boiled mode
At the main menu, hold L1 + L2 + R1 + R2 and press Triangle, Square, Left(2), Circle. Harder Boiled mode highly increases the challenge level, especially when used with the Super Cop difficulty setting.

Defeating people without guns
To defeat people that do not have guns easier, keep blocking and dodging. If you do not dodge, you will still get hurt. When you are in the prison, you will learn how to reverse a grab. This allows you to avoid getting hurt when they grab you. When you reverse the grab, you will throw their arms in the air. This will leave them open to attack (punch, kick, grab, etc.). However, they can still block.

Spine break
When you are locked up "Iron Point" and are walking around in the hall only two or three people will be around. One of them will run up to you and say something. When you run away, they start to walk away. As they walk away you can go in back of them and do the grab. However, they move too much and you will end up breaking their back

Well, there are all the cheats I know of for this game. Good luck and use them wisely!