In Michigan, as of April 1, 2010, the standard for capacity to make a trust and to make a will are the same, and that standard is relatively low. An individual who has a good idea of what his/her assets are, who their family members are and understands what the arrangements they are making are for is probably competent to make a will or trust as long as they are not under any duress or undue influence.
You should check to see what type of proceeding the attorney used to have a court appoint a guardian or conservator and who requested and paid for these services. Usually such an appointment requires that the court appoint a guardian ad litem to review the case for the judge and the submission of physicians statements unless your father was in agreement. You will also want to know who was appointed the guardian or cdonservator since this could involve fees, sometimes large in the case of a corporate fiduciary.