Here's just a small snippet from the Liberal Senate report, 2002:
https://sencanada.ca/content/sen/committee/371/ille/rep/summary-e.htm

"Cannabis alone, particularly in low doses, has little effect on the skills involved in automobile driving. Cannabis leads to a more cautious style of driving. However it has a negative impact on decision time and trajectory. This in itself does not mean that drivers under the influence of cannabis represent a traffic safety risk;"

Otherwise, I would suggest you read the Canadian Drug Policy Coalition's March publication:

Cannabis Use and Driving: Knowledge Translation Strategy Recommendations:
http://drugpolicy.ca/wp-content/uploads/2017/02/CDPC_Cannabis-and-Driving_Evidence-Review_FINALV2_March27-2017.pdf

And follow all the studies and references too; plenty of good info.