Legal action by the Samoan committee for the People Against Switching Sides or PASS could be the last opportunity to reverse the law to switch to driving on the left side of the road.
Opposition to the switch has been vocal, with thousand of people joining a rally in the capital Apia last week.
However, spokesperson Georgina Newton has reluctantly admitted that they may have run out of options.
"For most people in the committee we've come to the end of the road, we've only got the court case to go and if we can't win with the court case I think we have to sit back and make some decisions about what we're going to do in the future."
Last year PASS submitted a legal court action opposing the switch.
The case is still set to go ahead despite the Bill being passed.