What steps have to be taken to file a lawsuit against an employer when you are injured at work?

First, workers compensation covers all injuries that happen in the work place.  If your mother was hurt at work and a doctor has ties her injury to work then the employer's workers comp insurance carrier covers the medical bills and payments to her under the worker's comp statute.  The insurance company will be required to cover the medical bills until she has reached a maximum level of medical improvement or until she settles the claim for a lump sum amount.  She is not required to work at the job if the doctor places her on work restrictions (i.e. lifting over 25 lbs).  The employer is not required to force her to work those tasks.  Rather, the employer needs to give her jobs to do that she is capable.  If none exist, she must stay home.  If you mom is at home, she will be receiving money from her employer (75% of her net pay) as long as she is doing job searches to locate a new job she can do.  The employer is not allowed to fire her for not being able to work against the work restrictions.  If the employer does do that, the employer is subject to a lawsuit.  I suggest hiring a lawyer to help with the workers comp claim and to ensure that the employer isn't requiring her to do tasks outside her restrictions.  Speak to a lawyer ASAP.