Litigation: filing a lawsuit
Often, a personal injury case is settled by negotiation and agreement. Usually, this is done with an insurance company. Sometimes, you reach a point where you find that you cannot agree together with the liable party or his insurer. This may be about (the extent of) liability or the amount of compensation, for example. In addition to mediation is filing a lawsuit then the only option.
In principle, only lawyers are authorised and trained to litigate. So-called injury agencies and other injury specialists or lawyers are not!