the new low will come into___on the day when it is passed.

effect

law拼错了。。

这条法律会在通过生效。

还有。。law在通过前似乎不叫law。。叫议案。
而且句子里的when是多余的。

come into effect是短语。
生效;被实施
The new tax regulations came into effect last month.
新税法是上个月生效的。

effect
come into effect是固定词组。表示生效
The new law will come into effect on the day it is passed
新的法律将在它通过的那天生效