Exhibit 8.1

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

One Financial Center

Boston, Massachusetts 02111

617 542 6000

617 542 2241 fax

October 25, 2002

John Hancock Life Insurance Company

John Hancock Place

200 Clarendon Street

Boston, Massachusetts 02116

Re: John Hancock Life Insurance Company SignatureNotes/sm/

Ladies and Gentlemen:

At your request, we have examined the Registration Statement on Form S-3 (the “Registration Statement”), filed on April 3, 2002, as amended and supplemented through the date hereof, with the Securities and Exchange Commission in connection with the registration under the Securities Act of 1933, as amended, of $3,000,000,000 aggregate principal amount of debt obligations of John Hancock Life Insurance Company, a Massachusetts corporation (the “Company”). The Registration Statement is for the proposed issue and sale of SignatureNotes/sm/ which are due twelve months or more from the date of their issue (the “Notes”).

We have examined instruments, documents, and records that we deemed relevant and necessary for the basis of our opinion hereinafter expressed. Based on such examination, and subject to the following paragraph, the discussion in the Registration Statement under the heading “United States Federal Taxation” and in the Pricing Supplement dated October 24, 2002 under the heading “United States Federal Income Taxation”, subject to the limitations and qualifications described therein, constitutes our opinion as to the material United States federal income tax consequences of ownership and disposition of the Notes.

Our opinion is limited to the tax matters specifically covered under the heading “United States Federal Taxation” in the Registration Statement, and we have not been asked to address, nor have we addressed, any other tax matters. In addition, as indicated in the Registration Statement, the discussion sets forth our opinion as to the material United States federal income tax consequences of the ownership and disposition of the Notes as applied to original holders purchasing the Notes at the issue price and holding the Notes as capital assets as defined in Section 1221 of the Internal Revenue Code of 1986. Holders are advised to consult their own tax advisors with regard to the application of the income tax laws to their particular situations as well as any tax consequences arising under the laws of any state, local or foreign tax jurisdiction.

Boston    New York    Reston    Washington    New Haven

MINTZ, LEVIN, COHN, FERRIS, GLOVSKY AND POPEO, P.C.

John Hancock Life Insurance Company

October 25, 2002

Page 2

We hereby consent to the reference to our name and our opinion under the headings “United States Federal Taxation” and “Legal Opinions” in the Registration Statement and the filing of this opinion as an exhibit to the Registration Statement.

Very truly yours,

/s/    Mintz, Levin, Cohn, Ferris,

        Glovsky and Popeo, P.C.

Mintz, Levin, Cohn, Ferris,

Glovsky and Popeo, P.C.

Boston    New York    Reston    Washington    New Haven