Why is lying to a suspect legal?

Question

Can anyone tell me why, in the Marty Tankleff case back in 1988, why it was perfectly legal for the lead detective to lie to a 17 yr old kid, thus resulting in a false confession?

http://www.cbsnews.com/stories/2008/01/24/48hours/main3749128.shtml

Answer 1

The theory is that you won't admit to something you didn't do. For example, if police lied and said that they have witnesses who saw you killing someone, and you know you weren't there, you'd know they were lying.  

Answer 2

cops can lie to you all they want ,but if you lie its a crime ,just give them your name  and info and thats it .

Answer 3

its perfectly legal for the obvious reason the first one to answer your question stated the reason why.......if your innocent..why the h**l

if a cop said look  we know you bumped off your dad, he was always

on your back etc, and we have an eyewitness who says she saw you

do it..''AGAIN'' if you never harmed a hair on daddy's head...you will fight tooth and nail protesting being falsely accused...the cops will see

that and it would be duly noted this kids innocent.. Another reason they fudge when questioning a person is because, you may have information that you yourself isn't even aware of the relevance they may put on it...............false confession my f***y...no such animal

i don't care if i was questioned 23 hrs a day for 7 straight days..i still

ain't confessing, because i am tired, exhausted, want to go home,  want this all to go away...i still couldn't confess...i didn't do it.