Consider a society where the population includes a number of sentient androids, practically indistinguishable from humans in appearance. In practice, they are treated exactly like humans under most circumstances, with the exception that they are not legally considered as persons. One might not know whether someone is an android until they ask (which might be considered impolite), they cut them open (which is also impolite), or circumstances arise where they are requested to produce identity documents (which an android will not be able to do.)
Ideally, it should be possible for a human citizen to, say, have a friend who takes public transport to an office job in the cubicle next to them, and goes back home somewhere after work, but not know or care in particular whether this friend is a human or an android.
Inconveniences immediately arise: particularly obvious would be the problem that androids are legally not entities that may enter legal contracts*. In a generally well-meaning community, some sort of de facto standard or convention might suffice to keep things working as normal some of the time. For instance, an android may appear to have a job and be paid a salary for it, despite there existing no legally binding agreement referencing this employment, and being technically unprotected/unconstrained by the workplace regulations intended for humans. Everyone is happy so long as everyone plays along.
However, in the case where a contract is breached, it cannot be enforced. It might not be illegal to evict a rent-paying android without reason, because they are not technically a tenant. This would be unfair for the android, but is something from which the law would often protect a person. This question concerns the means with which a society might protect androids from abuse of a similar sort.
What mechanisms might be developed by a society such that androids reliably enjoy as many as possible of the privileges humans do, despite not being acknowledged by the law as such?
Perhaps, for instance, somehow making the aforementioned conventions enforceable, employing some social/market gymnastics such that violation of the would-be rights of an android always carries great enough cost to discourage exploitation? Alternatively, are there existing laws that may be appropriated/interpreted to this effect?
This worldbuild concerns a society in which androids are typically regarded as equals, and de facto share many/all of the rights of their human peers. However, as many comments and answers have pointed out, without (or even with) enforcement by written law, this tends to be an unstable condition in that it requires all of the members of the community to practice respect and kindness to maintain, but might be disrupted by just a few who seek to do so. The solution sought by this question are methods a society which has largely collectively agreed to protect androids as humans might adopt to discourage such disruptions.
* Forgive that I am extremely ignorant of the relevant topics. Should it be evident from the statements and examples given that I'm getting all this terribly wrong, please do inform me so that corrections may be made.