The classic example of safek de'oraysa le'chumra is when there is an agreement that a de'oraysa exists but there is a debate as to which cases constitute the de'oraysa. In such a debate we paskin le'chumra.
I would like to know about a debate whether a de'oraysa exists altogether or not. Would we say here safek de'oraysa lechumra and paskin that the de'oraysa exists?
My question (essentially) questions what "safek de'oraysa" means. What cases of "safek de'oraysa" do we pasken like the machmir position?
Just to spell it out a little more, I know we say "safek within an already established de'oraysa" lechumrah, but do we say "safek whether there is a de'oraysa or not" lechumrah?