Why couldn't Washington out law slavery at the state level?

[Jonty30]

I'm just trying to understand the relationship between the United States and the individual states on the issue of the legality of slavery at the state level. I know after the Civil War, the federal federal law trumped state law, but what about prior to the Civil War? Somebody told me the federal government was always the primary government when federal laws and state laws conflicted.

So, why couldn't the federal government just outlaw slavery at the state level instead of launching a civil war against the states?

[x]

Somebody told me the federal government was always the primary government when federal laws and state laws conflicted.

That depends on whether the law involves federal or state powers.

The distinction's gotten very murky over the years.

There are some areas where state law prevails, but a state law that sought to overturn federal regulations in an area where the federal government had authority would most likely be overturned by the courts, just as a federal law that usurped state powers would also be questioned by the courts.