a buon diritto

Italian

Literally, “at good right”.

with one's proper reasons; with good reason; not without cause
- 2007, David Foster Wallace, “La persona depressa [The Depressed Person]”, in Ottavio Fatica, Giovanna Granato, transl., Brevi interviste con uomini schifosi [Brief Interviews with Hideous Men], Einaudi:
  Da piccola, la persona depressa aveva necessitato di cure odontoiatriche, e ciascun genitore aveva preteso - a buon diritto, date le ambiguità medicee legali della normativa sul divorzio, aggiungeva sempre la persona depressa descrivendo la dolorosa battaglia fra i genitori riguardo alle spese per le sue cure odontoiatriche - che fosse l'altro a pagare.
  The depressed person's parents, for example, who had divorced when she was a child, had used her as a pawn in the sick games they played, as in when the depressed person had required orthodonture and each parent had claimed - not without some cause, the depressed person always inserted, given the Medicean legal ambiguities of the divorce settlement - that the other should pay for it.
  (literally, “As a small child, the depressed person had needed orthodontic care, and each parent had claimed - with good reason, given the Midecean legal ambiguities on the divorce provisions, the depressed person always added, describing the painful battle between her parents regarding the expenses for her orthodontic care - that the other one should pay for it.”)