When it comes to a business discriminating against a customer, the federal government has designated a number of demographics as protected. This means there can be civil and criminal consequences for businesses that refuse service based on these characteristics. They include the age, race, sex, nation of origin, etc.

The list doesn’t explicitly align with other regulation like equal employment opportunity, but they are close.

State laws generally reflect federal law in this area, however there are some jurisdictions, like DC and Seattle, where it would be illegal to refuse service based on political ideology.

It is also legal to call representatives and say if they vote a certain way, you will deny them service lol. Of course they don’t give a shit, but I still think that is nifty. It does not violate any extortion or bribery statute, and is protected under the first amendment right to free speech and governmental redress.

Discriminate away guise! And lobby through discrimination as well.