Parents caught up in a power struggle with a difficult teen often try one thing after another, searching for the right punishment to compel obedience. The problem with this approach is that it's just an escalation of the conflict and the teen can always respond with yet another escalation. Changing your whole approach to discipline may be more effective.
Use Consequences, Not Punishment
The first rule of effective punishment is to stop trying to use punishment, because it's not effective. A punishment is simply a retaliation for doing something that makes you angry. A consequence is the logical result of a bad decision your teenager made. For instance, if your teen gets home after curfew and you tell her she can't go on a trip she's been planning, that's just a punishment. If she's grounded for one week and then has an earlier curfew until she proves that she can be responsible about getting home on time, that's a consequence. Punishments only send the message that if your teen does something you don't like, you'll do something she doesn't like. Consequences teach your teen how to make better decisions while giving her the opportunity to make them.
Make the Rules With Your Teen
A common complaint of many teenagers is that parental rules are unfair or unreasonable. It's only natural for your teen to feel this way when he has no input into the rules under which he has to live. If you sit down with your teen to write a new set of household rules and the consequences for breaking those rules, you may be surprised by how strict he's willing to be with himself. If he breaks one of his own rules later on, he won't be able to say it's unfair when you apply the consequence.
Be Clear and Specific
When writing up a list of rules and consequences, be as clear and specific as you can be. For example, if you want your teenager to do more chores around the house, you should list exactly which chores she's expected to help with and which privileges depend on her completing her chores. "No television or Internet until kitchen is swept and dishes are done" is much more enforceable than "Try to help out more with sweeping and dishes."
Use Fool-Proof Consequences
Even if you approach every potential conflict with your child in the most reasonable way possible, some teens will still be defiant. A grounded teen could sneak out or even just storm out, and there isn't much you can do to prevent him. In this situation, it's best to have a few fool-proof consequences over which your teen has no control. If you pay for his cellphone, you can shut it off. If you provide an allowance, you can stop providing it. Consequences your teen has no power to defy can be used as a last resort, but the goal is to get your teen thinking about how to do better.