Singapore treats drug offences extremely severely. The death penalty is mandatory for those convicted of trafficking, manufacturing, importing or exporting more than 15g of heroin, 30g of morphine, 30g of cocaine, 500g of cannabis, 200g of cannabis resin and 1.2kg of opium. If you possess these quantities (and possession means you had control of them, regardless of how they ended up with you), you are deemed to be a trafficker and therefore subject to the death penalty. For unauthorised consumption, there is a maximum of 10 years’ jail or fine of S$20,000, or both. Note that you can be charged for unauthorised consumption as long as traces of illicit drugs are found in your system, even if you can prove that they were consumed outside the country.

Source: WikiTravel.org