Spanish private law lacks a general regulation of the rebus sic stantibus doctrine. The absence of regulation has not prevented Spanish courts to apply the doctrine and to adjust contracts to the situation caused by supervening adverse circumstances. However, the absence of a clear legal basis has blurred the distinction between the situation covered by the rebus doctrine and, specially, the case that impossibility doctrines intent to redress. Impossibility in contract law is generally ruled by article 1105 of the Spanish Civil Code. The article allows to the party affected by the impossibility to discharge the contact without incurring in contractual liability. This is clearly not the goal pursued by the rebus doctrines, but the renewed interest in such doctrines after the contractual crisis provoked by the pandemics, advises to distinguish between the cases of impossibility and those in which performance, though still possible, has become harder than expected

El artículo 1105 CC exonera de responsabilidad a quienes no pueden cumplir sus obligaciones por sucesos no previstos o que, aunque lo hubieran sido, son inevitables. El precepto incorpora, así, la regla general sobre la imposibilidad en el cumplimiento de las obligaciones en nuestro Código. La ausencia de una regulación de la cláusula rebus o sus equivalentes funcionales ha propiciado históricamente que la imposibilidad que contempla el artículo 1105 CC se empleara como el fundamento normativo –acaso, el pretexto– para ajustar el equilibrio contractual tras una alteración sobrevenida de circunstancias. Ahora que, a resultas de la pandemia, abundan las propuestas de regulación de la cláusula rebus en nuestro ordenamiento, parece pertinente deslindar esa figura de las doctrinas sobre la imposibilidad