The UNDT found that the main legal issue was whether ST/AI/2011/6 (Mobility and hardship scheme) applied to the counting of assignments that the Applicant undertook before the instruction went into effect on 1 July 2011. The UNDT found that ST/AI/2011/6 could not be applied retroactively to assignments that took place before it went into effect. The UNDT further found that the revised staff rule 4.8(b), which allows for different counting of the Applicant’s assignments, was applicable only to assignments starting on or after 1 July 2009, and was not retroactively applicable to prior...