Proportionate Sentencing is part of international human rights standard, yet the principle is routinely violated in many countries. The obvious breach is found in drug cases where the laws in some countries, including that of Thailand, mandates courts to base their sentences mostly on the quantity of drugs involved. There has been an effort in the last few years to amend Thai narcotics law to be more in line with the principle of proportionality in sentencing, resulting in the promulgation of the Narcotics Code which has entered into force since the 9th of December 2021. As the US and England both have attempted to reform their sentencing system to be more proportionate through the mechanism of ùsentencing guidelinesû, this article demonstrates how sentencing guidelines in the US federal system and England are utilised in drug cases. This comparative approach may shed some lights on how to correctly interpret and apply the provisions of the Narcotics Code, in accordance to the spirit of the principle of proportionality in sentencing.