Catalyst Paper (CTLFQ) S-8 Registration of securities for employees

Exhibit 5.1

Blake, Cassels & Graydon LLP

Barristers & Solicitors

Patent & Trade-mark Agents

595 Burrard Street, P.O. Box 49314

Suite 2600, Three Bentall Centre

Vancouver BC V7X 1L3 Canada

Tel: 604-631-3300 Fax: 604-631-3309

February 13, 2007

Catalyst Paper Corporation

16th Floor

250 Howe Street

Vancouver, BC V6C 3R8

Re:Registration Statement on Form S-8

We have acted as Canadian counsel to Catalyst Paper Corporation, a Canadian corporation (the “Company”), in connection with the Registration Statement on Form S-8 (together with any amendments thereto, the “Registration Statement”) under the Securities Act of 1933, as amended (the “Securities Act”), with respect to an aggregate of 10,000,000 common shares (the “Shares”) of the Company, which may be offered pursuant to the Company’s 1995 Stock Option Plan, as amended (the “Plan”). With your permission, all assumptions and statements of reliance herein have been made without any independent investigation or verification on our part except to the extent otherwise expressly stated, and we express no opinion with respect to the subject matter or accuracy of such assumptions or items relied upon.

In connection with this opinion, we have (i) investigated such questions of law, (ii) examined originals or certified, conformed or reproduction copies of such agreements, instruments, documents and records of the Company, such certificates of public officials and such other documents, and (iii) received such information from officers and representatives of the Company and others as we have deemed necessary or appropriate for the purposes of this opinion. In all such examinations, we have assumed the legal capacity of all natural persons executing documents, the genuineness of all signatures, the authenticity of original and certified documents and the conformity to original or certified copies of all copies submitted to us as conformed or reproduction copies. As to various questions of fact relevant to the opinions expressed herein, we have relied upon, and assume the accuracy of, representations and warranties contained in documents and certificates and oral or written statements and other information of or from representatives of the Company and others and assume compliance on the part of all parties to the documents with their covenants and agreements contained therein. We also have assumed that any future changes to the terms and conditions of the Plan will be duly authorized by the Company and will comply with all applicable laws.

Based upon the foregoing and subject to the limitations, qualifications and assumptions set forth herein, we are of the opinion that the Shares, when issued and paid for (with the consideration received by the Company being not less than the exercise price thereof) in accordance with the provisions of the Plan and the applicable agreements thereunder, will be duly authorized, validly issued, fully paid and non-assessable.

We are solicitors qualified to carry on the practice of law in the Provinces of British Columbia and Ontario. We express no opinion as to the laws of any jurisdiction other than the laws of the Provinces of British Columbia and Ontario and the federal laws of Canada applicable therein in effect on the date hereof.

The opinion expressed herein is given as of the date hereof, and we undertake no obligation to supplement this letter if any applicable laws change after the date hereof or if we become aware of any facts that might change the opinion expressed herein after the date hereof or for any other reason.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement. In giving such consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act.

Sincerely,

“Blake, Cassels & Graydon LLP”