"My grandmother was Polish" isn’t always the whole story
Poland’s descent route is a confirmation that citizenship was never lost - which means the whole case can turn on one fact nobody wrote down.
Polish citizenship by descent works differently from a simple grant. The state isn’t deciding whether to give you citizenship - it’s confirming that citizenship your ancestor held was never lost along the way to you. That framing sounds technical, but it changes what actually has to be proven.
Two facts decide most cases. First: did the ancestor hold Polish citizenship after the 1920 Citizenship Act came into force? Anyone who left the territory before 1920 was never a Polish citizen under this law, however Polish their family history feels. Second, and more often the deciding one: did that ancestor naturalize into another country’s citizenship before their child - the next link in the chain - was born? Poland’s pre-1951 rule treated foreign naturalization as an automatic loss of Polish citizenship. If it happened even a year before the child’s birth, the chain to that child, and everyone after them, was already broken.
This is why "my grandmother was Polish" is a true statement that can still produce a closed case: the relevant question isn’t whether she was Polish, but whether she was still Polish at one specific moment - her child’s birth. Family memory rarely preserves that kind of date.
For families whose ancestors came from the Kresy - the interwar eastern territories now in Ukraine, Belarus or Lithuania - there is an added layer: proving the ancestor was registered as a Polish resident there, rather than absorbed into Soviet citizenship after 1939. That single record is the most common reason a Polish case stalls, and the most common reason a family gives up on a claim that a different piece of paper would have settled.