I think police should be able to lie, but any response to a lie should be presumed a lie by the justice system. So, a lie can be used to get an undercover cop o

I think police should be able to lie, but any response to a lie should be presumed a lie by the justice system. So, a lie can be used to get an undercover cop out of trouble, but a lie cannot help an interrogation. Essentially, an officer of the law deciding to lie should invalidate all evidence gained after the lie.