Very easily, they have something called a company vehicle driving policy and this puts the onus on the driver to take breaks at specific hours and they often sneak it in when you read a contract of employment, or similar, and when you sign the document you have admitted having the policy and have not adhered to it which puts you at fault.
In the event of an accident one of the first questions is "how long have you driven" followed by "what breaks did you have and when" and with modern vehicle tracking methods its easy to download the data and if you lie the company has the tracking data to prove you have lied and once you lie you are stuffed, they can track you in many ways using current technology and if you breach your company policy you are culpable and not the company.
If you don't know your company vehicle driving policy then speak to your company H&S officer, or appointed person for H$S matters and demand a copy of their policy and stick to it, if anyone kicks up then throw their policy back at them.