To create a trust, certain legal requirements must be met. California Probate Code Section 15200 describes the ways in which a trust may be created:

Subject to other provisions of this chapter, a trust may be created by any of the following methods:

(a) A declaration by the owner of property that the owner holds the property as trustee.

(b) A transfer of property by the owner during the owner’s lifetime to another person as trustee.

(c) A transfer of property by the owner, by will or by other instrument taking effect upon the death of the owner, to another person as trustee.

(d) An exercise of a power of appointment to another person as trustee.

(e) An enforceable promise to create a trust.

Although there are a number of ways in which a trust can be created, there are a few other elements that must be satisfied:

• There must be a manifestation of intent by the Settlor (or Settlors, if a married couple) to create a trust. California Probate Code Section 15201.
• The trust must have property. California Probate Code Section 15202.
• The Trust may not be created for an illegal purpose or for a purpose that is against public policy. California Probate Code Section 15203.
• A trust created for an indefinite or general purpose is not invalid for that reason, if it can be determined with reasonable certainty that a particular use of the trust property comes within that purpose. California Probate Code Section 15204.
• There must be a beneficiary. California Probate Code Section 15205.

In California, trusts are not permitted to last indefinitely. Under California Probate Code Section 21205, a trust must not last longer than 21 years after an individual alive at the time the trust is created or 90 years, whichever is called for in the trust document. Here's the actual code section:

A nonvested property interest is invalid unless one of the following conditions is satisfied:

(a) When the interest is created, it is certain to vest or terminate no later than 21 years after the death of an individual then alive.

(b) The interest either vests or terminates within 90 years after its creation.

Understanding the elements of a valid trust can feel like an academic exercise, since it is virtually impossible to create an effective estate plan that carries out a client's wishes without necessarily meeting all of the elements. That being said, understanding the elements can help form an understanding of the considerations required in creating effective trusts.