Manuel Cedeño Berrueta Dec 19, 2018:

Co-perpetration is a distinct doctrine from conspiracy, although both are related to complicity, i.e. they are attempts to describe, through the language of criminal law, the participation of multiple individuals in a common criminal endeavor. A co-perpetrator is someone who pursues a criminal endeavor with at least one other confederate, sharing joint control over the operation. Following Roxin, cited by the Trial Chamber in Stakić, we can note the traditional view that co-perpetrators must be essential to the operation in question.11 In other words, they are necessary but not suffi cient conditions to the criminal plan’s continued success. A co-perpetrator cannot, by himself, bring the plan to fruition. It is for this reason that he needs fellow perpetrators to act in concert with him. The co-perpetrator’s role is also essential; if he refuses to participate, as Roxin notes, the operation is frustrated. He is therefore a necessary – but not sufficient – condition for completing the criminality. This is the essence of co-perpetration: a crime so large that no one individual can accomplish it on his own.
(https://scholarship.law.cornell.edu/cgi/viewcontent.cgi?arti...

Manuel Cedeño Berrueta Dec 19, 2018:

As Charles says, this text resembles criminal law language, but it’s not an actual criminal-law text.
Regarding the term “cómplice necesario”, you can see a definition here:

Cómplice necesario
Concepto penal que surge de la codelincuencia (v.) cuando el ejecutor material del hecho punible recibe la cooperación imprescindible o útil de otro para la perpetración del delito. Este otro es el denominado cómplice necesario por algunos penalistas y que el codificador no vacila en calificar de autor (v.) en la fórmula, dentro del Cód. Pen. esp., que establece esa equiparación personal y en la condena para "los que cooperan a la ejecución del hecho con un acto sin el cual no se hubiere efectuado". Tal es el caso del que conduce el vehículo desde el cual se ametralla a la víctima al pasar ante ella. (V. CÓMPLICE SECUNDARIO.)
(http://www.enciclopedia-juridica.biz14.com/d/cómplice-necesa...
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Which is similar to that of “co-perpetrator”:
Co-perpetration is a distinct doctrine from conspiracy, although both are related to complicity, i.e. they are attempts to describe, through the language of criminal law, the participation of multiple individuals in a co