
The article reveals the problem of issuing forensic expertise against the background of the conditions for admitting scientific evidence in a criminal trial on the example of the Polish and American legal systems. Both of these issues provide a comprehensive account of the issuance of an opinion for justice: on the one hand, revealing the challenges faced by the person who performs the expert opinion, and on the other hand, by the trial authority that has to “introduce and evaluate” this evidence into the process.