One major issue that can put a crimp in your Saturday night is a curfew law.
While not universal, curfew laws generally mean that people under the age of 18 are not allowed out in public or in business establishments after certain hours. If one or both people who are out on a date are affected by the curfew law, then it will mean that their date needs to end before the time in the law, or that the date has to move to a private establishment such as a person's home or apartment.
Age of Consent
While not necessarily a part of dating, sexual contact can be one aspect of a relationship.
The age of consent is the law that states individuals (both male and female) have to be a certain age before they can consent to any form of sexual contact. The oldest and most common age is 18, but some states or local jurisdictions might have laws that say people aged 16, or even 15, are old enough to be able to have sex if they consent to doing so. If one person is younger than the age of consent, then any sexual acts, consensual or otherwise, can be considered statutory rape.
There are some establishments that are off limits to people of a certain age.
While a 21-year-old man can walk right into a bar and order a drink for instance, he would not be able to bring his 20-year-old girlfriend in with him, even if she was not going to drink. The same rule can apply to establishments such as hookah lounges if one person on the date is younger than 18, which usually is the legal smoking age.