。
Collective responsibility is no responsibility.
Literal
Collective-responsibility [topic-は] no-responsibility.
A pithy social observation, structured as a simple nominal equation (X は Y) with the copula dropped — common in aphorisms and proverbs. The verb is implied. 連帯責任 is a compound meaning 'joint/collective liability'; the rhetorical punch is the paradox of pairing it with its opposite 無責任.