<PAGE>
(Letterhead of Cahill Gordon & Reindel)
December 18, 2000
Dean Witter Reynolds Inc.
Two World Trade Center
New York, New York 10048
Re: Morgan Stanley Dean Witter Select Equity Trust
Morgan Stanley High-Technology
35 Index Portfolio 2001-1
-----------------------------------------------
Gentlemen:
We have acted as special counsel for you as Depositor of the Morgan
Stanley Dean Witter Select Equity Trust Morgan Stanley High-Technology 35 Index
Portfolio 2001-1 (the "Trust"), in connection with the issuance under the Trust
Indenture and Agreement, dated September 30, 1993, and the related Reference
Trust Agreement, dated December 18, 2000 (such Trust Indenture and Agreement and
Reference Trust Agreement collectively referred to as the "Indenture"), between
you, as Depositor, and The Bank of New York, as Trustee, of units of fractional
undivided interest in said Trust (the "Units") comprising the Units of Morgan
Stanley Dean Witter Select Equity Trust Morgan Stanley High-Technology 35 Index
Portfolio 2001-1. In rendering our opinion expressed below, we have relied in
part upon the opinions and representations of your officers and upon opinions of
counsel to Dean Witter Reynolds Inc.
<PAGE>
-2-
Based upon the foregoing, we advise you that, in our opinion, when the
Indenture has been duly executed and delivered on behalf of the Depositor and
the Trustee and when the Receipt for Units evidencing the Units has been duly
executed and delivered by the Trustee to the Depositor in accordance with the
Indenture, the Units will be legally issued, fully paid and nonassessable by the
Trust, and will constitute valid and binding obligations of the Trust and the
Depositor in accordance with their terms, except that enforceability of certain
provisions thereof may be limited by applicable bankruptcy, insolvency,
reorganization, moratorium or other similar laws affecting creditors generally
and by general equitable principles.
We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement (File No. 333-50794) relating to the Units referred to
above and to the use of our name and to the reference to our firm in said
Registration Statement and the related Prospectus. Our consent to such reference
does not constitute a consent under Section 7 of the Securities Act, as in
consenting to such reference we have not certified any part of the Registration
Statement and do not otherwise come within the categories of persons whose
consent is required under said Section 7 or under the rules and regulations of
the Commission thereunder.
Very truly yours,
CAHILL GORDON & REINDEL