This is an interesting question, worded well (thanks @CodeGnome for editing) and highly relevant.
Unfortunately the answer is, like many questions regarding ideal practices, a firm "it depends".
It would depend on the
- Nature of the Development Team
- Existing Practices
- Organisation Culture
- Exact type of Agile implementation
- Individual personalities
Management are imposing practises upon the team
I would draw out two considerations;
A manager imposing particular types of technical practices may be forced to do so by an inflexible appraisal, bonus or review process.
Our organisation (and I suspect many Fortune 500 / FTSE 100) are committed to Continuous Improvement programs which mandate a CI target to be hit as part of the employee or department objectives. Therefore, regardless of our Retrospective or team decisions CI is a mandatory aspect of our work.
The situation can be complicated when the ScrumMaster, leading Sprint Retrospectives to improve team practices on behalf of the team can butt heads with the Line Manager of the team members because they feel like they own the working practices of the team and also write the appraisals.
I wish I had a fuller answer for you but I don't; it is a very tricky ledge to navigate.
If the team wish to adopt practices and management are challenging
I have banned any management from the Sprint Retrospective (even if they are part of the Scrum Team) and capture all of the feedback confidentially producing a highly sanitised Retrospective Report (less than 1 page). Normally, supported by the team, I unilaterally impose changes to the working practises of the team without speaking to management.
A Scrum version of "Ask forgiveness, not permission."
The team like this, it demonstrates the ScrumMaster will fight on their behalf and take the fight away from their work location and the truth is most managers are too busy to actually notice the micro-changes. It took the upper management 3 months to realise we had binned velocity completely from the Kanban Board and reports.
If a change is going to be a major undertaking and unlikely to fly under the management radar I would take a data-driven approach producing a Proposal which contrasts the current practice with the old specifically drawing out the benefits. Since Management never read it I also distil the proposal into a PowerPoint.
Normally any proposal would be backed up by a number of Lean Six Sigma models to demonstrate the benefits of the new approach. Managers respond to savings in time and/or money. If you can demonstrate that I don't think you will have any problems.