When considering how long the legal process can take once a lawsuit has been filed, it is important to remember that procedures and deadlines vary to some extent from place to place. Generally, the company or person sued has a deadline (often 20 to 30 days) to file a response in the court clerk's office.
The early phase of a lawsuit typically involves "written discovery" (questions and requests for records) exchanged between the parties' attorneys. Depositions are taken, usually after at least some degree of written discovery has taken place. Claimants are likely to be questioned in a deposition by the other side's attorney, but his or her attorney will prepare the claimant for that and will be present to make any needed objections and ask follow up questions. Doctors and experts may also give depositions.
A mediation may be held before trial. This is essentially a meeting, usually somewhat informal, with a neutral attorney who tries to help facilitate settlement discussions.
If the case does not settle, the trial is held. Unfortunately, it may take quite a long time after lawsuit filing for a trial to be scheduled; the length of time depends on the complexity of the case and the number of cases pending on that court's docket.
If the case proceeds to trial, once the trial is over, the losing party may have the right to appeal the decision to an appeals court. The appeals court, generally, is supposed to limit the scope of its decision to whether the trial judge made a mistake about the law. Again, a case on appeal can often take a long time before there is a ruling.