Using in Spain the intern to do a necessary job produces an employment relationship
There is a common employment relationship and not a training internship when productive activity is prioritized over training for the benefit of the intern and it could be claimed the corresponding payment of the salaries and even a compensation for moral damages. That, if it is considered proven that the internship holder performed tasks with total autonomy and alone (without tutorship), that the training consisted of carrying out tasks not training related and that the intern is adjusted to basically the work conditions of the rest of the personnel that is effectively hired.
Following the jurisprudence (precedents) of the Supreme Court, the key to differentiating between internship and employment contract is the purpose pursued in the granting of study aid, the objective of which is not to benefit from the interns' activity but to provide aid to their training. For the Supreme Court "the differential feature of the internship as perception is to facilitate the study and training of the interns and not to appropriate the results or fruits of their effort or study, obtaining from them a utility for their own benefit." If it is appreciated the typical notes of work in the activity of the intern and if there is alienation, dependence, onerousness and the company tries to conceal an employment contract under the guise of an internship, the interns can claim for the recognition of their rights and request for the corresponding amounts before the social jurisdiction, basically seeking the declaration as labor personnel and the payment of the salary differences.