If you don't speak Polish and you are a participant in court proceedings, you'll be assisted by an interpreter.
In criminal proceedings, whether you are a witness, a suspected person or you have been formally accused of a crime, you'll get a certified interpreter to assist you during any interrogation, interview or hearing in court. If there will be any important documents in Polish concerning you or your rights, they will be translated for you as well. You'll get the help of an interpreter as long as you don't speak Polish at all or your knowledge of the language is insufficient. If you speak it a little but don't feel comfortable in formal, court-related situations, you should always ask for an interpreter. Such assistance will be granted to you for free. An interpreter will also help you in communication with your legal counsel (if he'she doesn't speak your language) and will translate documents which you want to file with the court.
In civil procedure witnesses or a party to the proceedings who don't speak Polish (or speak it not good enough) will be examined by the court with the assistance of an interpreter. The judge may also decide that certain documents should be translated by a ceritfied translator and then order such translation. If you are a party to the proceedings and you want to submit documents in a language other than Polish, you should provide certified translations of such documents yourself. With regard to the costs of the interpreter's/translator's assistance, the general rule in civil proceedings apply: the person who has lost the case will bear the costs of the proceedings (icnluding the costs of translations) incurred by the winning party.