What are some current unjust laws?

This is a very subjective question, and my answer might not match your opinion. When forming your own answer about unjust laws, consider
Popular opinion: does the general populace find the law valuable, or oppressive?
Pragmatic effects: does the law cause more harm than it prevents?
Moral value: does the law adhere to moral codes, either societies or those espoused by a higher power?
Constitutionality: is the law consistent with the highest laws of the land?
Legitimacy: was the law passed by legitimate democratic means?
My personal answer for an unjust law hinges on the first four of those points. I believe that Civil Forfeiture is a profoundly unjust legal principle.
Civil Forfeiture allows police and other law enforcement officers to seize property of people not charged with a crime. Even if the people are innocent of that crime, they often cannot get their property back, because the property was charged with a crime, and the property does not have a right to a presumption of innocence. 
Popular opinion is almost universally opposed to Civil Forfeiture, and the primary effect is to encourage law enforcement to target lucrative 'criminals' rather than potentially dangerous ones. It's immoral to use a legal fiction to take innocent people's property, and the Constitution is supposed to protect American citizens from unjustified seizure. Unfortunately, the Supreme Court held that civil forfeiture was legal in 1966, and the Justice Department recently reverse guidelines restricting the practice.
https://www.aclu.org/issues/criminal-law-reform/reforming-police-practices/asset-forfeiture-abuse

https://www.newyorker.com/magazine/2013/08/12/taken

https://www.theatlantic.com/politics/archive/2017/07/sessions-forfeiture-justice-department-civil/534168/