Exhibit 5.1
               Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.

                                                                April 3, 2002

John Hancock Life Insurance Company
John Hancock Place
200 Clarendon Street
Boston, MA 02116

Ladies and Gentlemen:

         We have acted as counsel to John Hancock Life Insurance Company, a
Massachusetts corporation (the "Company"), in connection with the preparation of
a Registration Statement on Form S-3 (the "Registration Statement") filed by the
Company with the Securities and Exchange Commission (the "Commission") on April
3, 2002. The Registration Statement relates to the issuance and sale from time
to time, pursuant to Rule 415 of the General Rules and Regulations promulgated
under the Securities Act of 1933, as amended (the "Securities Act"), of up to
$3,000,000,000 in principal amount of the Company's SignatureNotes/sm/, which
are medium term notes with maturities of nine months or more from date of issue
(the "Notes"). The Notes are to be (i) issued under an Indenture to be entered
into between the Company and JPMorgan Chase Bank as trustee (the "Indenture"),
and (ii) sold pursuant to the terms of a Selling Agent Agreement to be entered
into among the Company and the agents named therein (the "Selling Agent
Agreement"). Forms of the Indenture and the Selling Agent Agreement are to be
filed as exhibits to the Registration Statement.

         In connection with this opinion, we have examined (i) the Registration
Statement; (ii) the Indenture; (iii) the Selling Agent Agreement; (iv) the
Company's Amended and Restated Articles of Organization, as currently in effect
(the "Articles of Organization"); (v) the Company's Amended and Restated Bylaws,
as currently in effect (the "Bylaws"); and (vi) resolutions adopted by the Board
of Directors of the Company (the "Board") relating to the filing of the
Registration Statement and related matters (the "Board Resolutions"). We have
also examined originals or copies, certified or otherwise identified to our
satisfaction, of such records of the Company, certificates of officers or other
representatives of the Company, certificates of public officials and others, and
such other agreements, documents, certificates and records as we have deemed
necessary or appropriate as a basis for the opinion set forth herein.

         In our capacity as counsel to the Company in connection with such
registration, we are familiar with the proceedings taken and proposed to be
taken by the Company in connection with the authorization and issuance of the
Notes. For purposes of this opinion, we have assumed that such proceedings will
be timely and properly completed, in accordance with all requirements of
applicable federal and Massachusetts laws, in the manner presently proposed.

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         In our examination, we have assumed the genuineness of all signatures,
the legal capacity of natural persons, the authenticity of all documents
submitted to us as originals, the conformity to original documents of all
documents submitted to us as certified or photostatic copies and the
authenticity of the originals of such copies.

         Members of our firm are admitted to the Bar of the Commonwealth of
Massachusetts, and we do not express any opinion as to the laws of any other
jurisdiction. No opinion is expressed herein with respect to the qualification
of the Notes under the securities or blue sky laws of any state or any foreign
jurisdiction. The Notes may be issued from time to time on a delayed or
continuous basis, but this opinion is limited to the laws, including the rules
and regulations thereunder, as in effect on the date hereof.

         Based upon and subject to the foregoing, we are of the opinion that,
with respect to any series of Notes, when (i) the Registration Statement, as
finally amended (including all post-effective amendments), has become effective;
(ii) an appropriate prospectus supplement with respect to the Notes has been
prepared, delivered and filed in compliance with the Securities Act and the
applicable rules and regulations thereunder; (iii) the terms of the Selling
Agent Agreement with respect to the issuance of the series of Notes have been
complied with by the Company and the selling agents; (iv) the Board, including
any appropriate committee appointed thereby, and the appropriate officers of the
Company have taken all necessary corporate action to approve the issuance and
terms of the Notes and all matters related thereto; (v) the terms of the Notes
and of their issuance and sale have been duly established in conformity with the
Indenture; and (vi) the Notes have been duly executed and authenticated in
accordance with the provisions of the Indenture, have been offered, issued and
sold in accordance with the terms of the Registration Statement, or any
post-effective amendment thereto, and any prospectus and prospectus supplement
relating thereto, have been issued and sold in accordance with the Indenture,
and have been delivered to the purchasers thereof upon payment of the agreed
upon consideration therefor in accordance with the Selling Agent Agreement, or
as otherwise contemplated by the Registration Statement, or any post-effective
amendment thereto, and any prospectus and prospectus supplement relating
thereto, the Notes will be legal, valid and binding obligations of the Company,
enforceable against the Company in accordance with their terms.

         The opinion set forth above is subject to the following exceptions,
limitations and qualifications: (i) the effect of bankruptcy, insolvency,
reorganization, fraudulent conveyance, moratorium or other similar laws now or
hereafter in effect relating to or affecting the rights and remedies of
creditors; (ii) the effect of general principles of equity, whether enforcement
is considered in a proceeding in equity or at law, and the discretion of the
court before which any proceeding therefor may be brought; (iii) the
unenforceability under certain circumstances under law or court decisions of
provisions providing for the indemnification of, or contribution to, a party
with respect to a liability where such indemnification or contribution is
contrary to public policy; (iv) we express no opinion concerning the
enforceability of any waiver of rights or defenses with respect to stay,
extension or usury laws; and (v) we express no opinion with respect to whether
acceleration of any Notes may affect the ability to collect any portion of the
stated principal amount thereof which might be determined to constitute unearned
interest thereon.

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         For purposes of the opinions rendered above, we have assumed that the
Company will at all times in the future be duly incorporated and validly
existing as a corporation under the laws of the Commonwealth of Massachusetts
and have the corporate power and authority to issue and sell the Notes.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to this opinion under the caption
"Legal Matters" in the prospectus included therein. In giving this consent, we
do not thereby admit that we are included in the category of persons whose
consent is required under Section 7 of the Securities Act or the rules and
regulations of the Commission promulgated thereunder.

         This opinion is furnished by us, as counsel to the Company, in
accordance with the requirements of Item 601(b)(5) of Regulation S-K under the
Securities Act and, except as provided in the immediately preceding paragraph,
is not to be used, circulated or quoted for any other purpose or otherwise
referred to or relied upon by any other person without our express prior written
consent.

                         Very truly yours,

                         /s/ Mintz, Levin, Cohn, Ferris,
                             Glovsky and Popeo, P.C.

                         Mintz, Levin, Cohn, Ferris,
                             Glovsky and Popeo, P.C.


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