"law in effect" is correct and usable in written English.
You can use it to refer to a law that is currently active. For example, "The new tax law is now in effect."
The law, in effect, makes it an open purchase".
But the city contended that its appeal triggered a stay keeping the new law in effect.
But with Dallas's new law in effect, Mrs. Tanner is also beginning to face some competition.
In the meantime, the offending domestic law in effect remains in force.
The law, in effect since 2002, granted exemptions to tens of thousands of religious academy students.
In 1991 a law, in effect, gave security for life to tenants and their children.
The law in effect makes it illegal to equate straight and gay relationships, and to distribute material on gay rights.
The Commerce Department, charged with developing regulations that put the law in effect, stands by its rules.
Still, Bell rightly notes that the act was an immigration law in effect as well as intent.
He's been replaced by Brett Kavanaugh, who voted in this case to keep a nearly identical law in effect.
They say the law in effect shields them from pressure by advocacy groups and politically active congregants to make endorsements.
