猥亵电话和恐吓电话是违法的。

Obscene and threatening phone calls are against the law.

《柯林斯英汉双解大词典》

比赛前给马服用兴奋剂是违法的。

It's illegal to drug horses before a race.

《牛津词典》

窃听无线电信息是违法的。

It is illegal to intercept radio messages.

《柯林斯英汉双解大词典》

It's illegal, so they can't sign that as a contract, but they they can just agree to do it.

因为是违法的,合同也就无效了,不过他们可以私下达成默契

耶鲁公开课 - 博弈论课程节选

Do you think that downloading should be absolutely illegal and prohibited?

你觉得下载是绝对违法的，应该禁止吗？

不能非法下载 - SpeakingMax英语口语达人

So even without there being an Attorney General, somebody might be awake in the justice department and notice that that's actually illegal.

就算是司法部长不知情,司法部门也会有人会发现,这样的协议是违法的

耶鲁公开课 - 博弈论课程节选