October 28, 2011
Arthur J. Gallagher & Co.
The Gallagher Centre
Two Pierce Place
Itasca, Illinois 60143-3141
In my capacity as Senior Counsel, Corporate & Securities, of Arthur J. Gallagher & Co., a
Delaware corporation (the Company), I am furnishing this opinion in connection with the resale registration of 47,000 shares (the Shares) of the Companys common stock, par value $1.00 per share (the
Common Stock), which shares may be sold from time to time by the selling stockholders described in the prospectus supplement of even date herewith (the Prospectus Supplement) filed by the Company with the
Securities and Exchange Commission and the related prospectus dated May 5, 2010 (the Base Prospectus and, together with the Prospectus Supplement, the Prospectus) that form part of the Companys
effective registration statement on Form S-3ASR (Reg. No. 333-166533) (the Registration Statement). I am delivering this letter pursuant to your request, in accordance with Item 601(b)(5) of Regulation S-K.
I have examined such documents, records and instruments as I have deemed necessary or advisable as a basis for expressing the opinion set
forth below. In arriving at this opinion, I have assumed the genuineness of all signatures, the authenticity of all documents submitted to me as originals and the conformity with the originals of all documents submitted to me as copies. As to
certain facts material to this opinion letter, I have relied without independent verification upon oral and written statements and representations of officers and other representatives of the Company.
Based upon the foregoing, and subject to the qualifications and limitations stated herein, I am of the opinion that the Shares are
validly issued, fully paid and non-assessable.
This opinion is limited in all respects to the General Corporation Law of the
State of Delaware (including the statutory provisions, all applicable provisions of the Delaware constitution and reported judicial decisions interpreting the foregoing), and I express no opinion as to the laws, statutes, rules or regulations of any
I hereby consent to the inclusion of this opinion letter as an exhibit to the Registration Statement and
the reference to me under the caption Validity of Securities in the Prospectus forming part of the Registration Statement. In giving these consents, I do not thereby admit that I am within the category of persons whose consent is
required under Section 7 of the Securities Act of 1933. This opinion is expressly limited to the matters set forth above and I render no opinion, whether by implication or otherwise, as to any other matters relating to the Company.
|Very truly yours,|
/s/ Seth Diehl
|Senior Counsel, Corporate & Securities|
Arthur J. Gallagher & Co.