Rule reminder
'In quanto' (inasmuch as / since / as) introduces a reason that inherently characterises the subject: 'In quanto esperto, dovrebbe saperlo' (as an expert, he should know). It can also introduce a clause. 'Giacché' (since / seeing that) is a literary/formal causal conjunction, interchangeable with 'poiché' in high-register writing. 'Posto che' (given that) + indicative introduces an established or hypothetical premise; in legal contexts it can introduce a condition.
What is the special feature of 'in quanto' compared to other causal conjunctions?