We need to distinguish both between criminal law and civil law and between specific and general laws.
Starting with criminal law:
The are surprisingly few specific laws relating to driving a motor vehicle. For example, there is no law that says you must drive on the left-hand-side of the road. If the police see you driving on the right, they (together with the CPS) must decide whether you have broken a 'general' law, through (for example) 'dangerous driving', 'driving without due care and attention' or 'driving without due consideration for other road users'. [So the driver of a milk-float, using the right-hand side of the road to make his deliveries on a well-lit deserted road at 5am, would not be breaking any laws].
There is definitely no 'specific' law requiring a driver to look in his mirror before opening the car's door. Further, most laws relating to driving don't apply once the vehicle is stationary and the engine is switched off. If the driver had caused injury or death to a cyclist or motorcyclist through opening his door, a charge of manslaughter or assault might follow. In the circumstances you refer to, a charge of 'criminal damage' might be appropriate as the Criminal Damage Act 1971 regards 'reckless' actions (as well as 'intentional' ones) as falling within the scope of the Act.
Moving on to civil law:
Whenever one person suffers loss or damage through the negligence of another person, he/she is entitled to demand compensation and (if necessary) to seek such compensation through the civil courts. Your friend has such a right to compensation if he can show that the other driver was negligent. However it needs to be remembered that good driving practice dictates that drivers overtaking parked vehicles should, wherever possible, pass wide enough to allow for the possibility of a door suddenly being opened (and that, as part of routine hazard awareness, drivers should be looking to see whether there are occupants of parked vehicles who might make such errors). A court might rule that the driver of the parked vehicle was only partly to blame for the accident.
Chris