<PAGE>
EXHIBIT 3.4
(ON CARTER, LEDYARD & MILBURN LETTERHEAD)
JUNE 8, 2000
The Chase Manhattan Bank,
as Trustee of
Nuveen Tax-Free Unit Trust,
Series 1170
4 New York Plaza, 3rd Floor
New York, New York 10004
Attention: Mr. Robert E. Lisk
Assistant Treasurer
Re: Nuveen Tax-Free Unit Trust, Series 1170
Dear Sirs:
We are acting as counsel for The Chase Manhattan Bank ("Chase") in
connection with the execution and delivery of a Standard Terms and Conditions of
Trust for Nuveen Tax-Free Unit Trusts Series 823 and subsequent Series (the
"Standard Terms and Conditions of Trust") dated September 7, 1995, and a related
Trust Indenture and Agreement (the "Trust Indenture and Agreement") dated
today's date (such Standard Terms and Conditions of Trust and related Trust
Indenture and Agreement are collectively referred to as the "Indenture"), each
between John Nuveen & Co. Incorporated, as Depositor (the "Depositor"), and
Chase, as Trustee (the "Trustee"), establishing the Nuveen Tax-Free Unit Trust,
Series 1170 (the "Trust Fund"), and the confirmation by Chase, as Trustee under
the Indenture, that it has caused to be credited to the Depositor's account at
The Depository Trust Company a number of units constituting the entire interest
in the Trust Fund (such aggregate units being herein called "Units") each of
which represents an undivided interest in the Trust Fund, which consists of
tax-exempt bonds (including confirmations of contracts for the purchase of
certain bonds not yet delivered and cash, cash equivalents or an irrevocable
letter of credit in the amount required for such purchase upon the receipt of
such bonds) in the aggregate principal amount set forth in the Closing
Memorandum executed and delivered today by the Depositor and the Trustee (the
"Closing Memorandum"), such bonds being defined in the Indenture as Bonds and
listed in the Schedules to the Indenture.
We have examined the Indenture, the Closing Memorandum, the form of
certificate for the Units included in the Indenture and a specimen of the
certificates to be issued thereunder (the "Certificates") and such other
documents as we have deemed necessary in order to render this opinion. Based on
the foregoing, we are of the opinion that:
1. Chase is a duly organized and existing corporation having the powers of a
trust company under the laws of the State of New York.
2. The Indenture has been duly executed and delivered by Chase and, assuming
due execution and delivery by the Depositor, constitutes the valid and legally
binding obligation of Chase.
3. The Certificates are in proper form for execution and delivery by Chase,
as Trustee.
4. Chase, as Trustee, has registered on the registration books of the Trust
Fund the ownership of the Units by The Depository Trust Company, where it has
caused the Units to be credited to the account of the Depositor. Upon receipt of
confirmation of the effectiveness of the registration statement for the sale of
the Units filed with the Securities and Exchange Commission under the Securities
Act of 1933, the Trustee may cause the Units to be transferred on the
registration books of the Trust Fund to such other names, and in such
denominations, as the Depositor may order, and may deliver Certificates
evidencing such ownership.
<PAGE>
5. Chase, as Trustee, may lawfully advance to the Trust Fund amounts as may
be necessary to provide periodic interest distributions of approximately equal
amounts, and may be reimbursed, without interest, for any such advances from
funds in the interest account, as provided in the Indenture.
In rendering the foregoing opinion, we have not considered, among other
things, whether the Bonds have been duly authorized and delivered or the federal
tax status of the Bonds.
Very truly yours,
CARTER, LEDYARD & MILBURN
