| 1.     |       | I have reviewed this annual report on Form 10-K of Legacy Reserves      LP (the “registrant”) for the year ended December 31, 2009;                                                                                                                                                                                                                |
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| 2.     |                                | Based on my knowledge, this report does not contain any untrue      statement of a material fact or omit to state a material fact necessary to      make the statements made, in light of the circumstances under which such      statements were made, not misleading with respect to the period covered by      this report;                                 |
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| 3.     |                                | Based on my knowledge, the financial statements, and other      financial information included in this report, fairly present in all      material respects the financial condition, results of operations and cash      flows of the registrant as of, and for, the periods presented in this      report;                                                    |
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| 4.     |                                | The registrant’s other certifying officer and I are responsible for      establishing and maintaining disclosure controls and procedures (as      defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal      control over financial reporting (as defined in Exchange Act Rules      13a-15(f) and 15d-15(f)) for the registrant and have: |
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|   |                                | (a)                                                                                                                                                                                                                                                                                                                                                            |       | Designed such disclosure controls and procedures, or caused such      disclosure controls and procedures to be designed under our supervision,      to ensure that material information relating to the registrant, including      its consolidated subsidiaries, is made known to us by others within those      entities, particularly during the period in which this report is being      prepared; |
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|   |                                | (b)                                                                                                                                                                                                                                                                                                                                                            |  | Designed such internal control over financial reporting, or caused      such internal control over financial reporting to be designed under our      supervision, to provide reasonable assurance regarding the reliability of      financial reporting and the preparation of financial statements for      external purposes in accordance with generally accepted accounting      principles; |
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|   |                                | (c)                                                                                                                                                                                                                                                                                                                                                            |  | Evaluated the effectiveness of the registrant’s disclosure controls      and procedures and presented in this report our conclusions about the      effectiveness of the disclosure controls and procedures, as of the end of      the period covered by this report based on such evaluation;  and |
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|   |                                | (d)                                                                                                                                                                                                                                                                                                                                                            |  | Disclosed in this report any change in the registrant’s internal      control over financial reporting that occurred during the registrant’s      most recent fiscal quarter (the registrant’s fourth fiscal quarter in the      case of an annual report) that has materially affected, or is reasonably      likely to materially affect, the registrant’s internal control over      financial reporting; and |
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| 5.     |                                | The registrant’s other certifying officer and I have disclosed,      based on our most recent evaluation of internal control over financial      reporting, to the registrant’s auditors and the audit committee of the      registrant’s board of directors (or persons performing the equivalent      functions):                          |
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|   |                                | (a)                                                                                                                                                                                                                                                                                                                                                            |  | All      significant deficiencies and material weaknesses in the design or      operation of internal control over financial reporting which are      reasonably likely to adversely affect the registrant’s ability to record,      process, summarize and report financial information; and |
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|   |                                | (b)                                                                                                                                                                                                                                                                                                                                                            |  | Any      fraud, whether or not material, that involves management or other      employees who have a significant role in the registrant’s internal control      over financial reporting. |

| Date: March 5, 2010 |                                        |
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|                | /s/ Cary D.      Brown                      |
|                | Cary D. Brown                               |
|                | Chief Executive Officer and Chairman of the |
|                | Board of Legacy Reserves GP, LLC,           |
|                | general partner of Legacy Reserves LP       |
|                | (Principal Executive Officer)               |

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