Under Article 9 of the Qatar Penal Code, the law that applies is generally the one in force at the time the offence was committed. However, there is an important and expat-friendly exception: if the law changes before a final judgement is issued in your case, and the new law is more favourable to you, then the new law will apply instead. This means you could benefit from reduced penalties or amended offence definitions if legislation changes during your proceedings.
Article 10 provides a counter-exception: if a new law is specifically issued to criminalise an act or impose harsher punishment, and that law is described as temporary or introduced due to exceptional/urgent circumstances, the more lenient rule does not apply — the stricter temporary law can still be enforced.
For continuous or ongoing offences (for example, a business operating illegally over a prolonged period), Article 11 states that a new law applies if the offending conduct continued into the period when the new law was in force. If you are involved in ongoing criminal proceedings, always keep your lawyer informed of any legislative updates, as a change in law could meaningfully affect the outcome of your case.
This is general legal information, not legal advice. For advice on your specific situation, consult a lawyer licensed in Qatar.