Exhibit 5.1

DLA Piper US LLP

The Marbury Building

6225 Smith Avenue

Baltimore, Maryland 21209-3600

T 410.580.3000

F 410.580.3001

W www.dlapiper.com

July 16, 2007

RAIT FINANCIAL TRUST

1818 Market Street, 28^th Floor

Philadelphia, Pennsylvania 19103

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as special counsel to RAIT Financial Trust, a Maryland real estate investment trust (the “Company”), in connection with the registration under the Securities Act of 1933, as amended (the “Securities Act”), pursuant to a Registration Statement on Form S-3 (the “Registration Statement”) to be filed with the Securities and Exchange Commission (the “Commission”) on the date hereof, including the preliminary prospectus included therein (the “Prospectus”), for the offering by the Company of up to 12,192,145 (the “Shares”) common shares of beneficial interest, $.01 par value per share, of the Company (“Common Shares”) that may be issued upon conversion of $425,000,000 aggregate principal amount of 6.875% Convertible Senior Notes due 2027 of the Company (the “Notes”). This opinion is being provided at your request in connection with the filing of the Registration Statement.

In connection with our representation of the Company, and as a basis for the opinion hereinafter set forth, we have examined originals, or copies certified or otherwise identified to our satisfaction, of the following documents (collectively, the “Documents”):

1. The Declaration of Trust of the Company, as amended, corrected and supplemented to date (the “Declaration of Trust”), certified as of a recent date by the State Department of Assessments and Taxation of Maryland (the “SDAT”);

2. The Bylaws of the Company (the “Bylaws”), certified as of the date hereof by the Secretary of the Company;

3. Resolutions of the Board of Trustees of the Company (the “Board of Trustees”), relating to the filing of the Registration Statement and the registration and issuance of the Shares (the “Trustees’ Resolutions”), certified as of the date hereof by the Secretary of the Company;

4. A certificate of the SDAT as to the good standing of the Company, dated as of the date hereof; and

RAIT FINANCIAL TRUST

July 16, 2007

Page 2

5. A certificate executed by the Secretary of the Company, dated as of the date hereof.

As used herein, the phrase “known to us” is limited to the actual knowledge, without independent investigation, of the lawyers in this firm who have provided legal services to the Company in connection with the Registration Statement.

In expressing the opinion set forth below, we have assumed the following:

1. Each individual executing any of the Documents, whether on behalf of such individual or another person, is legally competent to do so.

2. Each individual executing any of the Documents on behalf of a party (other than the Company) is duly authorized to do so.

3. Each of the parties (other than the Company) executing any of the Documents has duly and validly executed and delivered each of the Documents to which such party is a signatory, and such party’s obligations set forth therein are legal, valid and binding.

4. All Documents submitted to us as originals are authentic. All Documents submitted to us as certified or photostatic copies conform to the original documents. All signatures on all such Documents are genuine. All public records reviewed or relied upon by us or on our behalf are true and complete. All statements and information contained in the Documents are true and complete. There has been no oral or written modification or amendment to the Documents, or waiver of any provision of the Documents, by action or omission of the parties or otherwise.

5. The Shares will not be issued or transferred in violation of any restriction or limitation contained in Article VII of the Declaration of Trust.

6. The Company will reserve a sufficient number of authorized and unissued Common Shares for the issuance of the Shares upon conversion of the Notes.

Based upon the foregoing, and subject to the assumptions, limitations and qualifications stated herein, it is our opinion that:

1. The Company is a real estate investment trust duly formed and existing under and by virtue of the laws of the State of Maryland and is in good standing with the SDAT.

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July 16, 2007

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2. The Shares have been duly authorized and, when issued in accordance with and in the manner contemplated by the terms of the Notes and the resolutions authorizing their issuance, will be validly issued, fully paid and nonassessable.

The foregoing opinion is limited to the substantive laws of the State of Maryland and we do not express any opinion herein concerning any other law. We express no opinion as to compliance with the securities (or “blue sky”) laws of any jurisdiction. The opinion expressed herein is subject to the effect of judicial decisions which may permit the introduction of parol evidence to modify the terms or the interpretation of agreements.

We assume no obligation to supplement this opinion if any applicable law changes after the date hereof or if we become aware of any fact that might change the opinion expressed herein after the date hereof. This opinion is limited to the matters set forth herein, and no other opinion should be inferred beyond the matters expressly stated.

This opinion is being furnished to you for submission to the Commission as an exhibit to the Registration Statement.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the use of the name of our firm therein under the heading “Legal Opinions”. In giving this consent, we do not admit that we are within the category of persons whose consent is required by Section 7 of the Act.

Very truly yours,

/s/ DLA PIPER US LLP