Exhibit ll

[DECHERT LLP LETTERHEAD]

                             [FORM OF LEGAL OPINION]

________________, 2009

Board of Trustees
Janus Investment Fund
151 Detroit Street
Denver, Colorado 80206

Re: Janus Investment Fund on behalf of its [_____] series

Dear Ladies and Gentlemen:

We have acted as special counsel to Janus Investment Fund, a Massachusetts
business trust ("the Trust"), and we have a general familiarity with the Trust's
business operations, practices and procedures. You have asked for our opinion
regarding the issuance of shares of beneficial interest by the Trust in
connection with the acquisition by [_____], a series of the Trust, of the assets
of [_____], a series of the Janus Adviser Series, a Delaware statutory trust,
which shares have been registered on a Form N-14 Registration Statement (the
"Registration Statement") filed by the Trust with the U.S. Securities and
Exchange Commission on March 17, 2009.

We have examined originals or certified copies, or copies otherwise identified
to our satisfaction as being true copies, of various corporate records of the
Trust and such other instruments, documents and records of the Trust as we have
deemed necessary in order to render this opinion. We have assumed the
genuineness of all signatures, the authenticity of all documents examined by us
and the correctness of all statements of facts contained in those documents.

On the basis of, and subject to, the foregoing, it is our opinion that the
shares of beneficial interest of the Trust registered under the Securities Act
of 1933, as amended, in the Registration Statement, when issued in accordance
with the terms described in the Registration Statement, the Agreement and Plan
of Reorganization included therein, and the Trust's Rule 18f-3 plan as adopted
by the Board of Trustees of the Trust on __________ will be duly and validly
issued and outstanding, fully paid and non-assessable by the Trust.


US Austin Boston Charlotte Hartford New York Newport Beach Philadelphia
Princeton San Francisco Silicon Valley Washington DC EUROPE Brussels London
Luxembourg Munich Paris ASIA Beijing Hong Kong



We hereby consent to use of this opinion as an exhibit to the Registration
Statement and to all references to our firm therein.

Very Truly Yours,


/s/ Dechert LLP