This is the way I would translate it.
The meaning of immedesimazione organica is that
if something or someone exhibits the same characteristics as something or someone else, it must therefore belong to the same class of things as something else..it can be "integrated" or can be considered to be"inherent" to something else,
WordNet - Cite This Source inherent

adjective
1. existing as an essential constituent or characteristic; "the Ptolemaic system with its built-in concept of periodicity"; "a constitutional inability to tell the truth" [syn: built-in]
2. in the nature of something though not readily apparent; "shortcomings inherent in our approach"; "an underlying meaning" [syn: implicit in]

WordNet® 3.0, © 2006 by Princeton University.
Dictionary.com Unabridged (v 1.1) - Cite This Source
in·her·ent /ɪnˈhɪərənt, -ˈhɛr-/ Pronunciation Key - Show Spelled Pronunciation[in-heer-uhnt, -her-] Pronunciation Key - Show IPA Pronunciation
–adjective 1. existing in someone or something as a permanent and inseparable element, quality, or attribute: an inherent distrust of strangers.
2. Grammar. standing before a noun.
3. inhering; infixed.


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[Origin: 1570–80; < L inhaerent- (s. of inhaeréns), prp. of inhaerére to inhere; see -ent]

—Related forms
in·her·ent·ly, adverb


—Synonyms 1. innate, native, inbred, ingrained. See essential.

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www.fallacyfiles.org/adnazium.html

I am not aware of any specific legal terms for this other than
possibly "circumstantial evidence" but I do not think that it is wholly accurate in this context