Free people can say "no". Free people can refuse demands for their money, time, and children. Slaves cannot.
There is no freedom without the freedom to say "no". If someone demands that you do something and you can
say "no" and refuse to do it, then you are a free human being. If you can be forced to do something or
surrender something that you do not wish to, then you are a slave. No other test need be applied.