Network Rail (NR) is to be prosecuted over the 2007 Grayrigg train crash in Cumbria in which one passenger died.
The Office of Rail Regulation (ORR) said it had started criminal proceedings against NR for a breach of health and safety law which caused a Virgin Trains Pendolino train to derail near Grayrigg on February 23 2007.
Passenger Margaret Masson, of Glasgow, was killed and 86 people were injured, 28 seriously. Earlier investigations as well as last year's inquest into the death of Mrs Masson concluded that the derailment was caused by a poorly maintained set of points.
NR is facing a charge under section 3(1) of the 1974 Health and Safety at Work Act. The ORR said: "This results from the company's failure to provide and implement suitable and sufficient standards, procedures, guidance, training, tools and resources for the inspection and maintenance of fixed stretcher bar points."
The stretcher bars hold the moveable rails a set distance apart when the points are operated. The train that derailed was the 5.15pm London to Glasgow Central service.
The ORR railway safety director Ian Prosser said: "We have conducted a thorough investigation into whether criminal proceedings should be brought in relation to this derailment which caused the death of Mrs Masson and injured 86 people.
"Following the coroner's inquest into the death of Mrs Masson, I have concluded that there is enough evidence, and that it is in the public interest, to bring criminal proceedings against NR for a serious breach of health and safety law which led to the train derailment."
NR network operations managing director Robin Gisby said: "Network Rail has not hidden from its responsibilities. The company accepted quickly that it was a fault with the infrastructure that caused the accident. We again apologise to Mrs Masson's family.
"Since the derailment, we have worked closely with the authorities, conducted comprehensive and detailed investigations and made substantial changes to our maintenance regime. Today there is no safer form of travel than rail and it is important that the rail industry seeks ways to make it safer still."
Mrs Masson's son George welcomed the decision but said he had not received a personal apology. He said: "I'm going to attend the prosecution with other family members if they let the public in. Hopefully, this will bring an end to it, but it would've been all done for me if they had apologised to me face to face."