Maintaining relevance and avoiding the collection of excessive items of personal data is vital to the collection and processing of Personal Data because ' it might be useful' would contravene this Data Protection Principle. For example asking for both daytime and an evening telephone number. This is clearly irrelevant and excessive where the only telephone contact will be during the day and no emergency action may be required. The uncontrolled use of free format fields completed by end users may breach this principle and be particularly dangerous. The Fourth Principle Personal data shall be accurate and, where necessary, kept up to date.
Data are inaccurate if they are incorrect or misleading as to any matter of fact.
It is not always possible to have accurate and up to date data. However, data controllers must make reasonable efforts to ensure the accuracy of the data. Furthermore they must take appropriate steps to ensure that their data are kept up to date where this is necessary to address the notified purposes of the processing. If the data subject notifies the data controller of his or her view that the data are inaccurate, the data must either be corrected or indicate the view of the data subject. The Fifth Principle Personal data processed for any purpose or purposes shall not be kept for longer than is necessary for that purpose or those purposes.