Exhibit 5.1
2001 ROSS AVENUE
DALLAS, TEXAS
75201-2980
214.953.6500
FAX 214.953.6503
AUSTIN
BAKU
DALLAS
DUBAI
HONG KONG
HOUSTON
LONDON
MOSCOW
NEW YORK
RIYADH
WASHINGTON
August 18, 2005
Crosstex Energy, L.P.
2501 Cedar Springs
Suite 100
Dallas, Texas 75201
Ladies and Gentlemen:
We have acted as counsel to Crosstex Energy, L.P., a Delaware limited partnership (the
Partnership), Crosstex Energy GP, L.P., a Delaware limited partnership and the general partner of
the Partnership (the General Partner), and Crosstex Energy GP, LLC, a Delaware limited liability
company and the general partner of the General Partner (the Company), with respect to certain
legal matters in connection with the Registration Statement on Form S-8 (the Registration
Statement) to be filed by the Partnership with the Securities and Exchange Commission under the
Securities Act of 1933, as amended (the Securities Act), relating to 400,000 additional common
units representing limited partner interests of the Partnership (the Common Units) that may be
issued pursuant to the Companys Long-Term Incentive Plan, as amended (the Plan). At your
request, this opinion is being furnished to you for filing as Exhibit 5 to the Registration
Statement.
In our capacity as your counsel in the connection referred to above, we have examined the
Plan, the Partnerships Third Amended and Restated Agreement of Limited Partnership and the
Partnerships Certificate of Limited Partnership, each as amended to date, and originals, or copies
certified or otherwise identified, of partnership records of the Partnership, including minute
books of the Partnership as furnished to us by the Partnership, certificates of public officials
and of representatives of the Partnership, statutes (including the Delaware Revised Uniform Limited
Partnership Act) and other instruments and documents as a basis for the opinions hereinafter
expressed.
We have assumed that all signatures on all documents examined by us are genuine, that all
documents submitted to us as originals are authentic, that all documents submitted to us as copies
are true and correct copies of the originals thereof and that all information submitted to us was
accurate and complete.
Based upon our examination as aforesaid, and subject to the assumptions, qualifications,
limitations and exceptions herein set forth, we are of the opinion that, when issued and sold from
time to time in accordance with the provisions of the Plan, the Common Units will be duly
authorized, validly issued, fully paid and nonassessable.
The opinion set forth above is limited in all respects to the Revised Uniform Limited
Partnership Act of the State of Delaware and federal laws of the United States, and no opinion is
expressed herein as to matters governed by the law of any other jurisdiction.