This is not a political post. I am just asking a legal question. If I can alienate control of my body by allowing someone to kill me then why can't I allow myself to be enslaved? What is the legal distinction? Since slavery is just giving up control or allowing force against a body isnt that the same?
You don't cede control
You can't "alienate control of your body" - for example, a provision "Bob is allowed to kill me if certain conditions apply" would not be a legal contract. In euthanasia, where it's legal (and in most places it's not) you don't cede control or decisions. If you agree to assisted euthanasia, you just have someone else execute your decisions, they don't gain the power or right to make any decisions that they didn't already have.
The key difference from "allowing you to be enslaved" is that this implies that your current decision binds your future decisions. In euthanasia, if you'd "allow yourself to be killed" next friday, and changed your mind before that, then still proceeding with the act would be illegal, that would be murder. In a similar manner, a form of "slavery" where the slave is free to change their mind and go away as soon as they desire would be legal. It's comparable to e.g. BDSM practices where someone consents to pain, sexual acts, humiliation and control - that's legal if (and while!) the consent continues, but there's no legal way to irrevocably bind yourself to that consent.
What is the legal distinction? Since slavery is just giving up control or allowing force against a body isnt that the same?
Once enslaved, you will still be alive and therefore might change your mind, but you won't have the legal freedom to go back. This is a problem as, in a free society, you ought to have the ability to.
In case of euthanasia you will be dead and not able to change your mind to go back to life, hence the above problem does not exist.