SAVICKIS AND OTHERS v. LATVIA JUDGMENT [GC], no. 13378/05, § 60, ECHR 2008). However, only differences in treatment based on an identifiable characteristic, or “status”, are capable of amounting to discrimination within the meaning of Article 14 (see Carson and Others, cited above, § 61; Fábián, cited above, § 113, and Molla Sali, cited above, § 134). Furthermore, not every difference in treatment will amount to a violation of Article 14. A difference of treatment based on a prohibited ground is discriminatory if it has no objective and reasonable justification; in other words, if it does not pursue a legitimate aim or if there is not a reasonable relationship of proportionality between the means employed and the aim sought to be realised (see Andrejeva, cited above, § 81; Fabris v. France [GC], no. 16574/08, § 56, ECHR 2013; Fábián, cited above, § 113; and Molla Sali, cited above, § 135). 182. The Court also reiterates that the provisions of the Convention do not prevent Contracting States from introducing general policy schemes by way of legislative measures whereby a certain category or group of individuals is treated differently from others, provided that the interference with the rights of the statutory category or group as a whole can be justified under the Convention (see Andrejeva, cited above, § 83, and Ždanoka, cited above, § 112). Indeed, measures of economic and social policy often involve the introduction and application of criteria which are based on making distinctions between categories or groups of individuals (see J.D. and A. v. the United Kingdom, cited above, § 81). Moreover, Article 14 does not prohibit Contracting Parties from treating groups differently in order to correct “factual inequalities” between them (see Guberina v. Croatia, no. 23682/13, § 70, ECHR 2016, with further references). 183. The Contracting States enjoy a certain margin of appreciation in assessing whether and to what extent differences in otherwise similar situations justify a different treatment. The scope of the margin of appreciation will vary according to the circumstances, the subject matter and the background (see Stummer, cited above, § 88). First and foremost, the nature of the status upon which differential treatment is based weighs heavily in determining the scope of that margin (see Bah v. the United Kingdom, no. 56328/07, § 47, ECHR 2011). The margin is very narrow if the distinction is based on an inherent or immutable personal characteristic such as race or sex (see, for example, D.H. and Others v. the Czech Republic [GC], no. 57325/00 § 196, ECHR 2007-IV, and J.D. and A. v. the United Kingdom, cited above, § 89). The Court has applied the same standard to the criterion of nationality, holding that very weighty reasons would have to be put forward before the Court could regard a difference in treatment based exclusively on the grounds of nationality as compatible with the Convention (see Gaygusuz, § 42; Andrejeva, § 87; and Ribać, § 53, all cited above). Conversely, the margin of appreciation will be considerably wider, and the justification required will not be as weighty, if the status in question is subject to an element of personal choice, such as immigration status (see Bah, cited 61