What is required of a party who receives a Larger Work under the Mozilla Public License?

Question

Section 3.3 of the Mozilla Public License:

3.3. Distribution of a Larger Work

You may create and distribute a Larger Work under terms of Your choice, provided that You also comply with the requirements of this License for the Covered Software. If the Larger Work is a combination of Covered Software with a work governed by one or more Secondary Licenses, and the Covered Software is not Incompatible With Secondary Licenses, this License permits You to additionally distribute such Covered Software under the terms of such Secondary License(s), so that the recipient of the Larger Work may, at their option, further distribute the Covered Software under the terms of either this License or such Secondary License(s).

The Free Software Foundation makes this comment:

It's important to understand that the condition to distribute files under the MPL's terms only applies to the party that first creates and distributes the Larger Work. If it applied to their recipients as well, it would be a further restriction and incompatible with the GPL and AGPL.

Does this mean that the recipients of a Larger Work which is not under Secondary Licenses can freely violate the MPL's terms for the MPL-covered files, such as removing copyright notices or combining proprietary code with MPL code in the same file, and distribute the program as if the MPL had never been applied?

Answer 1

Does this mean that the recipients of a Larger Work can freely violate the MPL's terms for the MPL-covered files, such as removing copyright notices or combining proprietary code with MPL code in the same file, and distribute the program as if the MPL had never been applied?

You may be misreading the (rather convoluted) wording of the MPL-2.0, but none can blame you there ...

It simply means this: you have a choice of either the MPL-2.0 or the secondary licenses, if their terms are not incompatible. These secondary licenses are typically the GPL and LGPL.

There are three things you cannot escape: death, taxes ... and licenses!

These are essentially the same terms as in the Mozilla tri-license notice choice used before the MPL-2.0 in Firefox for instance where you could pick either one of the MPL-1.1, GPL or LGPL. But in the MPL-2.0 this is expressed in a generic way and baked into the license text as opposed to be in an external notice.

Now in a larger work, you can pick any license for your work but you still have to comply with the MPL. And you can use a secondary license choice (LGPL/GPL) if this is not incompatible with your own license.

If ...

I'm assuming that the Larger Work is not under any Secondary Licenses.

Then the MPL 2.0 and only the MPL 2.0 applies IMHO

For the sake of clarity if I were in your case I would state explicitly that only the MPL-2.0 applies there, but the MPL may already contains this in its own martian language.

If recipients of a Larger Work not under Secondary Licenses are not required to comply with the MPL, as noted by the FSF, can the recipient simply remove the MPL from the covered files?

No, unequivocally. This only applies to secondary licenses.

So let me restate one more time: the MPL 2.0 is essentially a choice of license. You can keep things under the MPL, a choice of MPL or secondary licenses or a secondary license. Period. Nothing else. You cannot escape the licensing terms of at least one or all of these.

The link you provide to the FSF commentary on the MPL 2.0 are in the context of the secondary (copyleft A/L/GPL) licenses and not for any other licenses. Do not misread this as related to other licenses.