This is only partially correct. The facts of the case are very important in determining the resulting decision

Berghuis v Thompkins (no implied invocation; implied waiver possible)

• Cops give good warnings and D declines to sign the waiver form

• They then questioned D for 3 hours and he pretty much stays silent but gives a few answers and head nods

• Then at the end of the questioning a cop asks him about God and D makes statement admitting he feels guilty for shooting a boy

• So can there be implied waiver of right to silence?

• D argued that he remained silent for so long that it was implied that he had invoked right to silent and they should have had to lay off to scrupulously honor his silence

• Court said you must have unambiguous expression of invocation of right to silence and silence isn’t enough to be invocation (no implied invocation)

• Court held that there COULD be implied waiver of right to silence under 3 circumstances:

1) if you got good warnings

2) as long as person has understanding of the rights and this understanding can be inferred from conduct and here his speaking and giving some answers was conduct that showed his understanding

3) no evidence of coercion

• So because D didn’t expressly invoke right to silence and he impliedly waived right, D’s waiver was valid & confession was allowed

TL:DR If you have been read your Miranda rights (meaning you are taken into custody and being interrogated) and you do not talk, that silence can not be brought in trial for any purpose. If you want to invoke your right to an attorney, it has to be clear and unambiguous. If you are sitting there and being quite the cops can still talk to you, and if you then confess you can't say "But I had invoked my silence".