Also is there any requirement as to whether the notes have to be kept in the officers own possession the entire time?
+++ This is not legal advice, only my opinion +++
2) When did they make the notes? (should be at the time of the event or shortly thereafter)
3) Have the notes been altered since they were made? (answer should be no)
4) Does the officer have an independent recollection of the events? (answer should be yes)
5) What are the notes required for? (answer should be to refresh the officer's memory)
No requirement for officer to have maintained personal possession of the notes. Some departments have officers keep notebooks in a common accessible area, some have them sent to offsite storage locations. And of course new e-tickets have electronic notes that are stored on a computer. Basically as long as the officer can identify the notes as theirs and that they've not been altered, they can use them.