A witness for opponents of the Samoan government's plan to switch the driving side says there will be a dramatic increase in road crashes following the change.
Motorists in Samoa will have to drive on the left side of the road instead of the right from September the 7th.
But the lobby group Pass is arguing in the Supreme Court that the change is unconstitutional on safety grounds.
The first witness to appear for the group, was Graham John Williams, a former New Zealand police officer who conducted research in Samoa in April.
Our correspondent in Apia, Autagavaia Tipi Autagavaia says he told the court there will be more accidents because safety preparations for the driving change have not been good. He raised some concerns from that research of no enforcement of the use of seatbelts in the country, and also a lack of remedial engineering, this is referring to the widening of roads out in the rural villages, and also poor visibility on some of the road bends on the island of Upolu.