Many companies wage wars against employees who leave them for other companies or independent ventures if there is a good reason to believe they are utilizing proprietary knowledge developed under their previous job. This issue raises many questions, especially in the software field. For instance, routines developed by software engineers in one job may be later used for other software, and different schemes may serve various applications. Many employees tend to keep private copies of material they participated in creating in their previous jobs. Such copies may later serve as evidence against them in potential legal suits. Many other employees diligently prepare business plans in their new jobs, specifying new developments they intend to make, only to find out later that to their surprise their previous employer is sometimes entitled to claim ownership of such ideas and developments, since they fall in the realm of their area of activity in their previous job, or as their ideas were developed during the normal business hours.
Moreover, many entrepreneurs naturally want to recruit workers from their previous places of employment, partially because they are familiar with the recruited workers. However, such recruitments may not only violate their employment contracts, but may also provoke indignation in the previous employer over other issues to which he or she had chosen to turn a blind eye until then (for example, the fact that the new venture was planned when the entrepreneurs were still employees of the company).