dcm4che and dcm4chee are licensed under an MPL/GPL/LGPL triple license - similar to Mozilla. This allows use of the files under the terms of any one of the Mozilla Public License version 1.1 (MPL), the GNU General Public License version 2 or later (GPL), or the GNU Lesser General Public License version 2.1 or later (LGPL).
The exception to this are the HL7 modules of the J2EE archive application (dcm4chee), which are built on the GPL licensed xhl7 classes provided by Gunther Schadow at the Regenstrief Institute and therefore can only be distributed under GPL.
Example license block from a source file:
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