Stephen, as posted above a claim is worth looking into. There is a chance that you can establish that the supermarket was liable for your sister's injuries if you can prove that precautions should have been taken by the supermarket to identify and clean up the puddle, but were not. Commonly in these types of cases, the supermarket will have in place systems whereby staff check the floors for spills etc or alternatively notify someone when a spill is identified so that patrons can be warned of its presence and it can be cleaned up quickly. If the systems they have in place are not reasonable or satisfactory (in the court's view) or if they did not stick to their systems they may be liable to pay damages to your mother in the form of compensation as detailed by Charles J. If you speak with a personal injury lawyer about this, they can start investigating whether or not you have grounds to make a claim.