Furthermore, the detaining authority will then be imposed with an ‘investigative duty’ to consider alternatives to detention. If necessary, “detention shall be as short as possible” and the detention of vulnerable groups requires additional motivation. Generally, the changes will harmonise Dutch legislation on the application of immigration detention more closely with the EU Returns Directive. 30. It is also important to note that immigration detention capacity of the Netherlands has declined from more than 3,000 cells detaining 12,485 persons in 2007 to 933 places in 2016.42 It is however impossible to establish how many stateless persons and persons at risk of statelessness are detained, due to the statistical concerns raised above and the lack of a statelessness determination procedure. Despite these positive developments which have brought Netherlands’ law and practice closer to its international and regional legal obligations, a number of problems remain deeply entrenched. 31. Alien detention in the Netherlands has the formal purpose of ensuring that people remain within sight of the government while preparing for their removal and should only be permitted where a real prospect of removal exists.43 Formally, it is only allowed as a measure of last resort, after it has been established that no less intrusive measures can be used.44 Contrary to the framework set out, evidence suggests that stateless persons are often detained without a thorough or realistic assessment of whether or how quickly deportation is possible as part of the administrative and judicial decision to do so. This puts stateless persons in a vulnerable position, as it is often impossible to safely remove stateless persons within a reasonable period of time, due to their statelessness status. 32. The lack of a statelessness determination procedure, is a significant concern in this regard, as the failure to identify statelessness or the risk of statelessness before a decision to remove or detain is made, often results in persons being arbitrarily detained. The new procedure, if integrally linked into the removal and detention decision making processes, would play a crucial role in this regard, by preventing the incarceration of persons whose return is a priori infeasible. 33. Immigration authorities moreover regularly assume return to be feasible for an entire population based on a single individual who received travel documents from the relevant State. In line with this is the general underestimation by removing (and detaining authorities) of the impact of noncooperation by diplomatic missions in removal proceedings. 34. The length of detention is also linked with the view to expulsion and may be longer for stateless persons. The EU Return Directive provides a number of clearly delineated instructions on the maximum length of detention, all of which have been transposed into national legislation: detention may not exceed six months initially but may be extended for another 12 months after judicial review. This extension may be approved due to a lack of cooperation, or because of “delays in obtaining the necessary documentation from third countries”, a criterion which appears to disadvantage stateless persons. Problematically, the ‘prospect of deportation’ is often defined liberally by both the authorities and the judiciary, regularly leading to lengthy detention without achieving the stated purpose of removal. Specifically persons whose citizenship status is more complex, including those at risk of statelessness, are more likely to be detained for disproportionately long periods. 42 ENS and ASKV, Protecting Stateless Persons from Arbitrary Detention in the Netherlands, 2015. Aliens Act 2000, Article 59. 44 EU Returns Directive, as also reflected in the proposed changes to Article 59 of the Aliens Act. 43