entries and exits at all of the external border crossing points of the 26 Schengen countries, nor are entry and exit records from national databases shared between countries. As a result, law enforcement officials continue to rely on checking passport stamps as the primary way to check that travellers who do not have the right of free movement have not exceeded their length of permitted stay in the Schengen Area. Regulation (EU) 2017/2226 envisages the establishment of an Entry-Exit System (EES) which will record third-country nationals' entries and exits when they cross the external borders of the Schengen Area in a central database, replacing passport stamps. As of August 2022, EES is expected to enter into operation at the end of May 2023. There are no systematic immigration checks when travelling between Schengen countries (i.e. crossing the internal borders of the Schengen Area). Passport stamps are never issued when travelling between Schengen countries, even when immigration checks between Schengen countries are temporarily re-introduced. When travelling to/from a non-Schengen country (i.e. crossing the external borders of the Schengen Area), the rules on stamping travel documents are as follows: Border officials are required, by law, to stamp the travel documents of third country nationals who do not qualify for one of the exemptions listed in the right hand column, even when border controls have been relaxed. Exceptionally, if stamping a person's travel document would cause serious difficulties (such as political persecution), border officials can instead issue a sheet of paper detailing the person's name, travel document number and entry date and location. However, in practice, border officials do not always stamp the travel documents of travellers as legally required. If a person who should have received an entry stamp cannot show one either upon request by a law enforcement officer or upon leaving the Schengen Area to a border official, the officer can presume that the person has been staying illegally in the Schengen Area and can expel him/her, unless the person can demonstrate using credible evidence (such as transport tickets and accommodation receipts) that he/she has not exceeded his/her permitted length of stay in the Schengen Area. Also, whilst by law persons enjoying the right of freedom of movement are not to receive a passport stamp, in practice, upon request, a stamp may be given – see the gallery below for an example of an entry stamp being issued upon request