The important distinction here is that at the point of impact, whether you were in the process of lane change OR you have completed the lane change.
If you were still in the middle of the lane change, then it is your fault. The other car that's already in the lane has the right of way, it is completely up to you to change lane safely. How long your signal light was on is not important.
If you have completed the lane change a good few seconds before the impact, then it is the other cars fault. Once the lane change was complete, then the crash had nothing to do with lane change. You can argue that he was speeding and failed to observe the traffic, thus causing the accident. Cars in the front have the right of way. If this is the case, don't even bring up the lane change, since lane change does not help your point, only weakens it.
The police should have recorded a diagram of the cars' crach position. Get the police report first, then formulate a strategy.
If you were still in the middle of the lane change, then it is your fault. The other car that's already in the lane has the right of way, it is completely up to you to change lane safely. How long your signal light was on is not important.
If you have completed the lane change a good few seconds before the impact, then it is the other cars fault. Once the lane change was complete, then the crash had nothing to do with lane change. You can argue that he was speeding and failed to observe the traffic, thus causing the accident. Cars in the front have the right of way. If this is the case, don't even bring up the lane change, since lane change does not help your point, only weakens it.
The police should have recorded a diagram of the cars' crach position. Get the police report first, then formulate a strategy.