The WWF says construction of the Don Sahong dam should be delayed by at least 10 years.
A provincial official says it was illegal for the court to sentence them for praying for the recovery of an ill woman.
The policy will be slowly and gradually rolled out across the rest of the country.
Authorities try to keep young Laotians from getting lured into the sex industry.
Authorities are targeting drug kingpins, local dealers and addicts in cities and rural areas.