9. A British sea fishery officer or a person assisting him by virtue of articles 6(2) or 7(1)(b) shall not be liable in any civil or criminal proceedings for anything done in the purported exercise of the powers conferred on him by virtue of articles 6, 7 or 8 if the court is satisfied that the act was done in good faith, that there were reasonable grounds for doing it and that it was done with reasonable skill and care.