Halakha Ulangan 14:4: Mishneh Torah, Forbidden Foods & Sefer HaChinukh

Blut
Wer Blut vom Quantum einer Olive isst, verwirkt, wenn er es absichtlich tut, die Strafe der Vertilgung (Karet); wenn es aber unabsichtlich geschah, muss er das gewöhnliche Sühnopfer darbringen. Es ist jedoch ausdrücklich in der Schrift erklärt, dass die Straffälligkeit nur auf das Blut von Hausvieh, Wild und Geflügel steht, wobei zwar kein Unterschied zwischen reinem oder unreinem stattfindet, denn es heißt: »Und was nur Blut ist, sollet ihr nicht essen in allen euren Wohnorten bei Geflügel und Hausvieh«. Wilde vierfüßige Tiere sind aber unter dem Ausdrucke Vieh mitbegriffen, denn es heißt: »Folgendes ist das Vieh, das ihr essen dürfet: Ochs .... Hindin und Hirsch«. Das Genießen des Blutes von Fischen, Heuschrecken, kriechenden und krabbelnden Tieren hingegen, bewirkt keine Strafe, daher ist das Blut ersterer geradezu erlaubt zu essen, selbst wenn man es in ein Geschirr sammelte und es als Speise isst; das Blut von unreinen Heuschrecken und Fischen ist bloß deswegen für den Genuss verboten, weil es einen Bestandteil ihres Körpers, ganz wie die Milch eines unreinen Haustieres, ausmacht; — das Blut kriechender Tiere ist ganz wie deren Fleisch für den Genuss verboten, wie wir es bereits erklärt.

From the laws of the commandment is that which they, may their memory be blessed, said (Zevachim 70a) that Scripture did not distinguish with an impure beast or animal between its meat and its chelev — as it is all forbidden. And [regarding] flesh of a person, his flesh is not included in the prohibition of an impure beast, to transgress a negative commandment for it, even though man is called a living (or animal) soul and he does not bring up the cud or completely divide [his foot]. And therefore, we do not administer lashes for one who eats from his flesh or drinks from his chelev — whether alive or dead. But it is nonetheless forbidden with a positive commandment, as behold Scripture numbered seven species of animals and stated about them (Deuteronomy 14:4), “These are the animals that you may eat.” And a negative commandment that comes from the implication of a positive commandment, is a positive commandment. This is the opinion of Rambam, may his memory be blessed (Mishneh Torah, Laws of Forbidden Foods 2:3). But Ramban, may his memory be blessed, wrote (Ramban on Leviticus 11:3) that there is not even a positive commandment about the flesh of a man. And he brought a proof from that which they, may their memory be blessed, said (Keritot 21a), “There is not even a commandment of separation from the blood and chelev of those that walk on two [legs].” And he, may his memory be blessed, wrote that the law is the same for flesh, that it is permitted like the blood. As if not, how could blood be permissible — and as they, may their memory be blessed, said (Keritot 22a), “Blood that is between the teeth, he should suck and swallow” — and it is established for us (Bekhorot 5a), “All that comes out of the impure is impure.” And nonetheless, the flesh of the dead (Israelite) is forbidden to benefit from. And the rest of his proofs are in his book. And the rest of the details of the commandment are elucidated in the third chapter of Chullin and in other places. (See Mishneh Torah, Laws of Forbidden Foods 2.)