Usage patterns
〈事〉の前に無力だto be powerless in the face of something
Humans are powerless before the forces of nature.
〈事〉に対して無力だto be powerless against something
Modern medicine is powerless against this disease.
自分の無力を痛感するto keenly feel one's own powerlessness
Unable to do anything, I keenly felt my own powerlessness.
無力を感じるto feel powerless
I felt powerless in front of the large organization.