It’s always a real hazard outside building sites and car boot sales. The law is simple enough. If somebody places mud on the carriageway, and it causes a foreseeable harm, then the person who places the mud (or indeed any other slippery substance) on the carriageway is liable for the damages arising from the mud. Foreseeability is a requirement which gets lawyers – well, me at least – excited, as there’s a 1972 case, which still remains good law, that says there’s no requirement for foreseeability.
The real problem is tracing who put the mud on the carriageway. Imagine the mud is between two fields in an agricultural area and every morning and every evening Farmer Palmer drives his 200 head of dairy cattle from the top field to the bottom field, across the road that you just slipped off on. Provided that you can show the state of the road was muddy, then Farmer Palmer is going to be liable. It becomes a matter of evidence rather than law.
Where it becomes rather more tricky is if you cannot source the mud. If there is mud or another slippery substance randomly in the middle of the carriageway, then this becomes a Motor Insurers Bureau untraced drivers claim. The most likely cause of the substance in the middle of the carriageway is that it has been dropped by a road going vehicle, and road going vehicles have to be insured. The fact that the offending vehicle has disappeared means this becomes an MIB untraced claim.
Where things get really tricky is where there are competing sources for the mud. Was it deposited by a farmer? Was it dropped on the carriageway off a trailer? Has it washed onto the road through natural process? If deposited by a farmer or a builder, then he is liable. If it was dropped off a trailer, then the driver of the towing vehicle is liable. If he cannot be traced, then the MIB. If the material has just washed onto the road then no one is liable, and it is very unlikely to be a local authority liability. The local authority owes no duty to keep the surface of the road clear from contaminants, including mud. It only has to look after the “fabric of the road”.