It appears that Aphria has options in the "unlikely event" of any CDS policy change.  

The following paragraphs are excerts from iAnthus statement....

iAnthus is aware of speculation surrounding CDS; specifically, media reports have suggested that CDS may be considering a policy change which, if implemented, could disqualify CDS settlement of securities of issuers with U.S. cannabis assets.

On the facts, CDS has not issued any policy statement indicating that it is formally considering a policy change to disqualify the settlement of securities of issuers with U.S. cannabis assets. Likewise, none of the securities regulators in Canada have issued a formal statement on settlement rules pertaining to issuers with U.S. cannabis assets. Simply put, at this time we are not aware of any formal decision by CDS, or any of the securities regulators in Canada, to disqualify or restrict settlement of securities of issuers with U.S. cannabis assets.

CDS is highly regulated by various securities regulators in Canada including the Ontario Securities Commission, the Autorit des marchs financiers, and the British Columbia Securities Commission. Accordingly, even if CDS wanted to unilaterally implement a policy change it is not readily apparent that CDS has the authority to do so.

iAnthus recently obtained eligibility with The Depository Trust Company ("DTC") in April 2017, allowing iAnthus to facilitate trading and settlement for iAnthus shareholders. DTC is the largest securities depository in the world and holds over US$35 trillion of securities on deposit. Many Canadian brokerages are fully equipped for and settle through both CDS and DTC, and in the event of any CDS policy changes, iAnthus expects to be able to clear trades through DTC.

To see the press release in full please click on the the following link:

iAnthus Addresses Speculation Surrounding CSE Listing Policies and CDS Policy on Settlement of Securities