“免于受罚”可以翻译为“be exempt from punishment” 或者 “escape punishment”。
“be exempt from punishment” 强调的是由于某种原因（如法律规定、特殊情况等）而免除受罚，带有一种正式、合法的意味。
“escape punishment” 则更侧重于描述实际没有受到惩罚这一结果，相对更口语化、更直接。
例句：
He was exempt from punishment due to his young age.（他因年纪小而免于受罚。 ）
The criminal managed to escape punishment and is still at large.（那个罪犯设法逃脱了惩罚，至今仍在逃。 ）