at the expense of
US /æt ðə ɪkˈspens ʌv/
UK /æt ðə ɪkˈspens ʌv/

1.
a expensas de, a costa de
resulting in harm or damage to (someone or something else)
:
•
He pursued his career at the expense of his family life.
Él persiguió su carrera a expensas de su vida familiar.
•
The company increased profits at the expense of environmental regulations.
La empresa aumentó las ganancias a expensas de las regulaciones ambientales.