Laboratory notebooks are increasingly kept electronically. Electronic laboratory notebooks (ELN) offer advantages over documentation on paper. However, they have the disadvantage that digitally stored data can be changed easily and undetectably and its depiction is dependent on hardware and software. The question, how ELN accessibility, completeness, integrity, authenticity, readability and interpretability of data can be ensured in the long term, was addressed by an interdisciplinary workgroup. Physicists, computer scientists and jurists examined together, how probative and sustainable long-term archiving of digital primary research data could be realized. Presented are concepts and design information for the development of probative ELN. They were analyzed for technical feasibility, compliance with user requirements and compliance with the legal framework.