This research looks at the issue of determining the admissibility of the evidence that is obtained as a result of the private detective activities in civil proceedings in the light of the privacy which is guaranteed by the Constitution of the Russian Federation and a ban on collecting information about privacy, including on the Internet. Despite the fact that the private detectives' Law develops and periodically changes, it is imperfect: there are no specific rules in civil proceedings which are governing the use of the evidence that is obtained by private detectives. The grounds for the lawfulness of collecting information about privacy are suggested in the article, and also court practice which is relating to the use of the results of a private detective activity as evidence in court is considered.