RT vs. CT

If you see an illegal act by Defendant, use constructive trust.
A BFP of chattel from a thief will not acquire title. ---> true owner use replevin
since BFP is not a wrongdoer, don't use constructive trust or equitable lien.
BFP is good guy. Don't use CT/EL to good guy.

Resulting T:
1. Purchase money RT
2. failure of an express T
3. incomplete disposition of res

Constructive T:
when there is a wrongful conduct
Theft
Conversion
Fraud Duress
Undue Influence
Mistake
Breach of Fiduciary Duty
Homicide(wills)