1) If the tenant begins occupancy on the 13th of Nisan, whose obligation is the BC – the landlord who owns the property, or the tenant who will be living there on Pesach?
Halacha: It’s a matter of the timing of both the transaction and access to the property. If the transaction is effective by the evening of the 14th (i.e. the time for BC), AND the landlord has handed over the key by then, the obligation rests on the tenant. If not, the obligation remains with the landlord. (Note: Regarding bitul/nullification, both the landlord and tenant should have any chametz in that property in mind.)
2) If the tenant begins occupancy on the 14th (so that BC is the obligation of the landlord), can the tenant trust that the landlord fulfilled his obligation?
Halacha: If the tenant can contact the landlord and ask him (or his family members – see #4), he should do so to be certain. If the landlord cannot be contacted, the tenant may presume that BC was performed. However, it must be within the time that the tenant can still do a bitul, in order for this presumption to be valid. (Ed: See further explanation about this stipulation in “Important caveat” below.)
3) In the previous scenario (#2), suppose the tenant discovered that indeed, the landlord DID NOT DO the BC, can the tenant “sue” the landlord? Is the tenant obligated to do BC now himself?
Halacha: NO, he may not sue (i.e. the tenant has no recourse on the grounds that the “contract” was was not honored. And YES, the tenant must now do the BC himself (unless he can get the landlord to come out and do his duty.) (Ed: See MBY 435 where we learned that BC can be done past the appointed time as well.) The operative principle here, says the Gemara, is: “A person is always willing to perform a mitzvah, even if it costs money!”
4) Also in scenario #2, suppose the tenant was informed that the landlord DID the BC, but the “informer” was someone who is not a valid witness by Jewish law – e.g. a woman or minor – is his/her word valid in this context?
Halacha: Not only are they believed in this case, but even if they say that they did the BC, that is accepted as well. This is interesting, especially in the case of a minor! (Note: The minor must have already reached the age of ‘chinuch’ / mitzvah education, i.e. 6-7 years old.)
Important caveat: In every case where a leniency is granted for BC – particularly in cases #2 and #4 – this is only when a bitul has, or still can be, made. We have previously learned that whenever a bitul is made, the BC is only required rabbinically and is thus subject to leniency in extenuating circumstances. However, if bitul was not made and is no longer possible, e.g. the tenant became aware that the landlord did not perform BC, and it already past the bitul deadline (the end of the fifth hour on Erev Pesach), then the BC obligation is on the Torah level, and no leniencies can be granted. Thus, in those two cases, the tenant would be obligated to do BC!