Usually follow the preponderance of evidence (przewaga prawdopodobieństwa). If your version is 60–70% more likely than the other party's, the court may rule in your favor.
Witness testimonies, explanations from the accused, and expert opinions. MateriaЕ‚ dowodowy
In Polish law, a general rule applies: and is not contrary to the law can be admitted as evidence. This includes: explanations from the accused
The "weight" of evidence required differs significantly between the two: and expert opinions. In Polish law