<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-07-25</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001018332</issuerCik>
        <issuerName>L-1 IDENTITY SOLUTIONS, INC.</issuerName>
        <issuerTradingSymbol>ID</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001374987</rptOwnerCik>
            <rptOwnerName>Rose Boykin</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O L-1 IDENTITY SOLUTIONS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>177 BROAD STREET, 12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>STAMFORD</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06901</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2011-07-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>23417</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.00</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On July 25, 2011, L-1 Identity Solutions, Inc., a Delaware corporation (the &quot;Issuer&quot;), was acquired (the &quot;Merger&quot;) pursuant to that certain Agreement and Plan of Merger, dated as of September 19, 2010 (the &quot;Merger Agreement&quot;), by and among the Issuer, Safran SA, a french societe anonyme (&quot;Parent&quot;), and Laser Aquisition Sub Inc., a Delaware corporation and wholly owned subsidiary of Parent (&quot;Merger Sub&quot;).  In connection with the Merger, all shares of the Issuer's common stock, par value $0.001 per share (&quot;Common Stock&quot;), held by the Reporting Person at the effective time of the Merger (the &quot;Effective Time&quot;) were exchanged for merger consideration consisting of $12.00 in cash per share of Common Stock, subject to applicable withholding amounts, as described in the Merger Agreement.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>B. Boykin Rose</signatureName>
        <signatureDate>2011-07-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
