Your cert looks fishy. Replacing it with another one (ECDSA too, of course) leads to successful decoding.
https://play.golang.org/p/xVICqXPJfg

These are the commands we used to generate the cert:

openssl ecparam -name prime256v1 -genkey -param_enc explicit -out dev-ca.key
openssl req -new -sha256 -x509 -days 10000 -key dev-ca.key -out dev-ca.crt -subj "/C=US/ST=California/L=San Francisco/O=Chain/OU=development/CN=Development Root Certificate Authority"

It looks like the param_enc explicit flag in openssl ecparam is what causes the error.

Go assumes that an ECDSA curve as specified in a certificate is always going to be a named curve.

Named curves are only one of 3 valid ways of specifying a curve, according to RFC 5480, but the only way to do so for x.509 certificates:

The parameter for id-ecPublicKey is as follows and MUST always be
present:

ECParameters ::= CHOICE {
namedCurve OBJECT IDENTIFIER
-- implicitCurve NULL
-- specifiedCurve SpecifiedECDomain
}
-- implicitCurve and specifiedCurve MUST NOT be used in PKIX.
-- Details for SpecifiedECDomain can be found in [X9.62].
-- Any future additions to this CHOICE should be coordinated
-- with ANSI X9.

The failing certificate uses param_enc explicit, which translates to using a specified curve when encoding the AlgorithmIdentifier.

openssl perhaps shouldn't be willing to generate this certificate. That said, maybe go should have a better error in the case of encountering such a certificate?

https://go-review.googlesource.com/c/57050 makes a more useful error message here.

Change https://golang.org/cl/57050 mentions this issue: crypto/x509: improve error when parsing bad ECDSA cert