"evidence gathering phase" is a correct and usable phrase in written English
You can use it when talking about the part of a process where evidence is being collected or compiled for a specific purpose. For example, "The police unit is currently in the evidence gathering phase of their investigation."
In May, in approving a settlement of the class-action lawsuit by the models, who contended that several model agencies colluded to fix prices, the federal judge in the case reduced legal fees to $3.8 million from the roughly $9 million requested, in part out of concern over the conduct of plaintiff lawyers during the case's evidence-gathering phase.
The BICI has lost the support of many Bahrainis during the evidence-gathering phase.
Key researchers across the United Kingdom were involved in the first "evidence-gathering" phase of the action plan.
An important outcome of the evidence-gathering phase was the building and refinement of information systems that informed – and continue to inform – many aspects of strategic direction.
Through using the framework it should be quite apparent that, for example, the latest media report of a new gene-disease association is only at the start of the evidence-gathering (Phase 0), and thus deserves little of the precious clinical time available for determining current patient care options.
If data is available, the ideal time to consider CEA is during the evidence gathering and synthesizing stage.
So it needs a totally different form of evidence gathering.
This paper discusses shortfalls in relation to the requirements gathering phases of simulation.
The evidence gathering followed, rather than informed, the decision making.
Afterwards, she thanked the PSNI for "three years of tireless investigation and evidence gathering".
But there won't be a need for such evidence gathering in the future, right?
