Protein before and after workout
Having a protein before your workout will allow you to have more energy, resulting in your workouts feeling stronger, but you will not burn as much fat when you workout.
After your workouts, it is commonly accepted that your body acts like a sponge for about an hour while your muscles attempt to collect nutrients to repair what was torn down during the workout. That is why it is important to have a quality source of protein immediately after your workouts.
I would tend to say having your protein after your workouts is more important.
If you are fat and/or you had a decent meal within the last 3 or 4 hours, that protein drink before a workout is not really needed because your body has energy stored up and ready to burn.
If you are very lean and/or cutting calories to drop some weight, then you are likely to show up at the gym with no energy. To prevent this, take 10 to 25 grams of protein 30 to 60 minutes before going to the gym. This does not need to be 100% protein, and it would even be good to have some carbs in there to help make you feel pumped in the gym.