Which one of the following scenarios would be a violation of the Sixth Amendment?

a. Suspect’s apartment is searched without a warrant. 
b. ?A defendant’s lawyer is not permitted to cross-examine a witness. 
c. ?A defendant is tried in state court a second time for a crime of which he was acquitted. 
d. ?A defendant is put on trial without formal charges being filed. 

b. ?A defendant’s lawyer is not permitted to cross-examine a witness.