Answer: If a state made a previously-illegal activity, such as gambling or prostitution legal, then, other things equal, GDP will increase.
Step-by-step explanation:
GDP is the gross domestic value of a service offered or goods bought. Since the service or good was illegal before the price was cheaper since there was no taxes or other parties involved. Since the services and goods are now legal, the prices can be changed and will, most likely, be higher. There will be people out to make a profit and the workers will want more money. Incentives will be given for people to use the now legal services and goods and more money will be spent.