> if you can call the police or get the authorities to intervene... then it's no...

> if you can call the police or get the authorities to intervene... then it's not slavery.

I'm not sure this definition pans out. This would mean slavery cannot happen in a country where it's not legal.

Take an unfortunate whose been enslaved in a nation where it's legal. They're kept in a basement, chained to a table, made to work every waking hour.

One day, that nation passes a law making slavery illegal.

While this person's situation has not changed one iota, using your definition they were a slave yesterday and not a slave today.

In fact, since 1981 there is no nation in the world where slavery is legal.[1] So, using this definition strictly...slavery literally does not exist.