Since 6th April 2016 all dog owners in England, Scotland and Wales have to have their dog microchipped and register them with a government compliant microchip database such as Petlog.
All puppies must be microchipped and recorded on a microchip database by the time they are 8 weeks old.
If a keeper of a dog which is not microchipped gets served with a notice requiring them to have the dog chipped, they will have 21 days to do this .The owner of an unchipped dog will be given 21 days to comply and failure to do so may result in a fine of up to £500. Note that the microchip database may not show the owner of a dog. This is why the term keeper is used the mirochip is not proof of ownership.
It is the responsibility of the owner to ensure that contact details for the dog/dogs are kept up to date to ensure a dog can be reunited with its owner in the event that it is lost or stolen. Any changes to an owner’s contact details must be updated on their microchip database to ensure compliance with the law. If a dog owner subsequently moves, changes contact telephone number, etc. then the dog is no longer considered microchipped under the new law and enforcement can be taken.
The words 'legally responsible' are used if your dog strays, bites or causes any unjust damage. As the keeper of the dog you are 'liable' for the dog that is registered to you. Therefore, as the 'keeper' you will be held responsible if your dog has been found to commit such an act, however the 'keeper' will be protected from prosecution if their dog attacks a burglar or trespasser on their land.