Facts

Parties and proceedings: The marriage of the parties [A.A.] (appellant, born 1976) and [B.A.] (respondent, born 1980) was concluded in 2006. Children [C.A.] (born 2009) and [D.A.] (born 2011) were born of the marriage. The parties separated in 2017; the separation was regulated by court order (decision of the District Court President Thal-Gäu dated 24 January 2018).

Employment situation and relocation: From May 2018 until the end of June 2019, the appellant worked through temporary employment agencies for three employers ([E. AG] , [F. AG] , [G. AG] ). He was in debt, and his wages were garnished. In July 2019 he returned to Germany, where he did not engage in any gainful employment and received Hartz IV benefits.

Course of proceedings: On 30 August 2019 the appellant filed the divorce action. The District Court President dissolved the marriage on 27 January 2020, left the children under joint parental authority, placed them in the custody of the mother, and obliged the father to pay child maintenance (from 1 September 2019: CHF 750.-- and CHF 550.--, from 1 September 2021 CHF 650.-- each). The appellant's appeal, which requested a determination of CHF 248.-- per child, was dismissed by the Cantonal Court of Solothurn, Civil Chamber, on 2 June 2020 (ZKBER.2020.29). By civil law appeal to the Federal Supreme Court dated 6 July 2020, the appellant requested the amendment of the maintenance contributions, alternatively remittal, and in addition an advance on court costs of CHF 5'000.-- and legal aid. No responses were requested.

Subject matter of the dispute: It was disputed whether a hypothetical income in the amount of the salary last earned in Switzerland (CHF 4'500.--) may be imputed to the appellant, who resides in Germany, as well as complaints of violation of the duty to state reasons (Art. 29 para. 2 Cst.) and of fundamental rights (Art. 8, 10 para. 2, 24 Cst.).

Considerations

Admissibility: This is a final decision of a superior cantonal court in civil matters (Art. 72 para. 1, Art. 75 paras. 1 and 2, Art. 90 FSCA). The amount in dispute of CHF 30'000.-- is reached (Art. 74 para. 1 lit. b FSCA). The civil law appeal was lodged within the time limit and in the required form (Art. 100 para. 1 FSCA). The Federal Supreme Court does not enter into the request for an advance on court costs, as it concerns a substantive legal claim which must be asserted before the cantonal court of first instance (BGE 143 III 617 E. 7).

Duty to state reasons: The complaints of insufficient reasoning are dismissed. A decision is sufficiently reasoned if the affected party can recognise its scope and challenge it appropriately; not all submissions of the parties must be refuted (BGE 142 III 433 E. 4.3.2; 145 III 324 E. 6.1). The reference to a Federal Supreme Court decision on freedom of establishment is comprehensible in the overall context. The appellant was moreover able to challenge the decision appropriately.

Fundamental rights: The fundamental rights (Art. 8, 10 para. 2, 24 Cst.) have no direct effect between private persons; protection is provided through civil law (BGE 143 I 217 E. 5.2). The complaints therefore carry no independent weight; what remains to be examined is the violation of Art. 133 in conjunction with Art. 276 and Art. 285 CC.

Hypothetical income: Particularly high requirements apply to the exhaustion of earning capacity vis-à-vis minor children (BGE 144 III 481 E. 4.7.7; 137 III 118 E. 3.1). A relocation abroad remains disregarded if gainful employment in Switzerland would be possible and reasonable (Art. 285 CC). A hypothetical income may also be imputed in case of a reduction in income: in case of a reversible reduction regardless of its cause; in case of an irreversible reduction only where there is intent to cause harm (malicious, abusive conduct; BGE 143 III 233 E. 3.4). Intent to cause harm must be proven by unequivocal indications (circumstantial evidence, internal fact).

Assessment by the cantonal court: The cantonal court found that the appellant's assertions regarding dismissal, unemployment and lack of support were unsubstantiated. He was a trained cook with many years of professional experience in three sectors, had left…