idiom "need for"

[vaibhav.iit2002]

Is idiom "need for" correct?
I think "need of" is correct, but not sure about "need for".

e.g.
129. As litigation grows more complex, the need for experts to explain technical issues becomes more apparent.

[punitkaur]

I think it depends on the usage

For sentences like these-

I am in need of a pill. " in need of " sounds correct.

Another sentence with "need for"

There is an immediate need for the president to respond to the public's outrage regarding the health insurance issue.