During trials parties typically exchange PDFs of demonstratives prepared in PowerPoint for openings, witness examinations, and closings. While these PDFs can capture some of the animated steps in a slide deck, and sometimes even include video added to slides, much of the content of the PowerPoint presentation will inevitably be omitted from the PDF version. If you'd like to, or are required to, send out a PowerPoint file with the full functionality of the original, but don't want the recipients to be able to edit the file, OfficeOne has an add-in called Shape Locker that will allow you to lock it down and make it impossible to alter.
Shape Locker will appear on the Design Tools tab on the PowerPoint ribbon.

If you select the objects on a slide and then click on 'Lock Shapes' you will be prompted to indicate how you want to lock down each selected shape. You can configure the presentation so that shapes cannot be resized, repositioned, or even selected, and so that text can't be edited.

The add-in is not free - a single user license costs $49, but a trial version is available. The trial version lasts for 11 days.
I tried running some vba code to select all of the shapes in a PowerPoint file at once, but this did not allow me to use Shape Locker on all slides automatically. It's necessary to lock the shapes on each slide one by one.
I've tested it out, and confirmed that I could not edit text after running it, or select any object at all on a slide. However it was possible to access the Animation pane in PowerPoint and make changes there.